modify

dc6ec7d3 · 宋海霞 · dc6ec7d3 · dc6ec7d3 · dc6ec7d3 · dc6ec7d3
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
+version: 2
+config_android:
+  docker:
+    - image: circleci/android:api-28
+  working_directory: ~/project
+  environment:
+    JAVA_TOOL_OPTIONS: "-Xmx1024m -XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap"
+    GRADLE_OPTS: "-Dorg.gradle.daemon=false -Dorg.gradle.workers.max=2 -Djava.util.concurrent.ForkJoinPool.common.parallelism=2 -Dkotlin.incremental=false"
+    TERM: dumb
+setup_ftl:
+  - run:
+      name: Authorize gcloud and set config defaults
+      command: |
+        echo $GCLOUD_SERVICE_KEY | base64 -di > ${HOME}/gcloud-service-key.json
+        sudo gcloud auth activate-service-account --key-file=${HOME}/gcloud-service-key.json
+        sudo gcloud --quiet config set project ${GOOGLE_PROJECT_ID}
+jobs:
+  build_and_setup:
+    docker:
+      - image: circleci/android:api-28
+    working_directory: ~/project
+    environment:
+      - JAVA_TOOL_OPTIONS: "-Xmx1024m -XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap"
+      - GRADLE_OPTS: "-Dorg.gradle.daemon=false -Dorg.gradle.workers.max=2 -Djava.util.concurrent.ForkJoinPool.common.parallelism=2 -Dkotlin.incremental=false"
+      - TERM: dumb
+    steps:
+      - checkout
+      - run:
+          name: Build test and lint
+          command: |
+            ./gradlew assembleMockDebug assembleProdDebug assembleMockDebugAndroidTest testMockDebug testProdDebug lintMockDebug lintProdDebug
+      - run:
+          name: Save test results
+          command: |
+            mkdir -p ~/junit/
+            find . -type f -regex "./.*/build/test-results/.*xml" -exec cp {} ~/junit/ \;
+          when: always
+      - store_test_results:
+          path: ~/junit
+      - store_artifacts:
+          path: ~/junit
+          destination: tests
+      - store_artifacts:
+          path: ./app/build/reports
+          destination: reports/
+      - persist_to_workspace:
+          root: .
+          paths:
+            - ./app/build
+  run_ftl:
+    docker:
+      - image: circleci/android:api-28
+    working_directory: ~/project
+    environment:
+      - JAVA_TOOL_OPTIONS: -Xmx1024m
+      - GRADLE_OPTS: -Dorg.gradle.daemon=false -Dorg.gradle.workers.max=2 -Dkotlin.incremental=false
+      - TERM: dumb
+    steps:
+      - attach_workspace:
+          at: .
+      - run:
+          name: Authorize gcloud and set config defaults
+          command: |
+            echo $GCLOUD_SERVICE_KEY | base64 -di > ${HOME}/gcloud-service-key.json
+            sudo gcloud auth activate-service-account --key-file=${HOME}/gcloud-service-key.json
+            sudo gcloud --quiet config set project ${GOOGLE_PROJECT_ID}
+      - run:
+          name: Test with Firebase Test Lab
+          command: |
+            BUILD_DIR=build_${CIRCLE_BUILD_NUM}
+            sudo gcloud firebase test android run \
+              --app app/build/outputs/apk/mock/debug/app-mock-debug.apk \
+              --test app/build/outputs/apk/androidTest/mock/debug/app-mock-debug-androidTest.apk \
+              --results-bucket cloud-test-${GOOGLE_PROJECT_ID}-blueprints \
+              --results-dir=${BUILD_DIR}
+      - run:
+          name: Download results
+          command: |
+            BUILD_DIR=build_${CIRCLE_BUILD_NUM}
+            sudo pip install -U crcmod
+            mkdir firebase_test_results
+            sudo gsutil -m mv -r -U `sudo gsutil ls gs://cloud-test-${GOOGLE_PROJECT_ID}-blueprints/${BUILD_DIR} | tail -1` firebase_test_results/ | true
+      - store_artifacts:
+          path: firebase_test_results
+workflows:
+  version: 2
+  build_and_test:
+    jobs:
+      - build_and_setup
+      - run_ftl:
+          requires:
+            - build_and_setup
--- a/.gitignore
+++ b/.gitignore
+*.iml
+.gradle
+local.properties
+.idea
+.DS_Store
+build
+captures
+.externalNativeBuild
--- a/.travis.yml
+++ b/.travis.yml
+language: android
+android:
+  components:
+  - tools
+  - platform-tools
+  - build-tools-28.0.3
+  - android-28
+  - extra-android-m2repository
+  - extra-google-m2repository
+jdk:
+- oraclejdk8
+script:
+- ./gradlew test
+before_cache:
+- rm -f $HOME/.gradle/caches/modules-2/modules-2.lock
+cache:
+  directories:
+  - $HOME/.m2
+  - $HOME/.gradle/caches/
+  - $HOME/.gradle/wrapper/
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
+# How to become a contributor and submit your own code
+
+## Contributor License Agreements
+
+We'd love to accept your patches! Before we can take them, we 
+have to jump a couple of legal hurdles.
+
+### Before you contribute
+Before we can use your code, you must sign the
+[Google Individual Contributor License Agreement](https://cla.developers.google.com/about/google-individual)
+(CLA), which you can do online. The CLA is necessary mainly because you own the
+copyright to your changes, even after your contribution becomes part of our
+codebase, so we need your permission to use and distribute your code. We also
+need to be sure of various other things—for instance that you'll tell us if you
+know that your code infringes on other people's patents. You don't have to sign
+the CLA until after you've submitted your code for review and a member has
+approved it, but you must do it before we can put your code into our codebase.
+Before you start working on a larger contribution, you should get in touch with
+us first through the issue tracker with your idea so that we can help out and
+possibly guide you. Coordinating up front makes it much easier to avoid
+frustration later on.
+
+### Code reviews
+All submissions, including submissions by project members, require review. We
+use Github pull requests for this purpose.
+
+### The small print
+Contributions made by corporations are covered by a different agreement than
+the one above, the
+[Software Grant and Corporate Contributor License Agreement](https://cla.developers.google.com/about/google-corporate).
--- a/LICENSE
+++ b/LICENSE
--- a/README.md
+++ b/README.md
+# Android Architecture Blueprints v2
+<p align="center">
+<img src="https://github.com/googlesamples/android-architecture/wiki/images/aab-logov2.png" alt="Illustration by Virginia Poltrack"/>
+</p>
+
+Android Architecture Blueprints is a project to showcase different architectural approaches to developing Android apps. In its different branches you'll find the same app (a TODO app) implemented with small differences.
+
+In this branch you'll find:
+*   Kotlin **[Coroutines](https://kotlinlang.org/docs/reference/coroutines-overview.html)** for background operations.
+*   A single-activity architecture, using the **[Navigation component](https://developer.android.com/guide/navigation/navigation-getting-started)** to manage fragment operations.
+*   A presentation layer that contains a fragment (View) and a **ViewModel** per screen (or feature).
+*   Reactive UIs using **LiveData** observables and **Data Binding**.
+*   A **data layer** with a repository and two data sources (local using Room and remote) that are queried with one-shot operations (no listeners or data streams).
+*   Two **product flavors**, `mock` and `prod`, [to ease development and testing](https://android-developers.googleblog.com/2015/12/leveraging-product-flavors-in-android.html) (except in the Dagger branch).
+*   A collection of unit, integration and e2e **tests**, including "shared" tests that can be run on emulator/device or Robolectric.
+
+## Variations
+
+This project hosts each sample app in separate repository branches. For more information, see the `README.md` file in each branch.
+
+### Stable samples - Kotlin
+|     Sample     | Description |
+| ------------- | ------------- |
+| [master](https://github.com/googlesamples/android-architecture/tree/master) | The base for the rest of the branches. <br/>Uses Kotlin, Architecture Components, coroutines, Data Binding, etc. and uses Room as source of truth, with a reactive UI. |
+| [dagger-android](https://github.com/googlesamples/android-architecture/tree/dagger-android)<br/>[[compare](https://github.com/googlesamples/android-architecture/compare/dagger-android#files_bucket)] | A simple Dagger setup that uses `dagger-android` and removes the two flavors. |
+| [usecases](https://github.com/googlesamples/android-architecture/tree/usecases)<br/>[[compare](https://github.com/googlesamples/android-architecture/compare/usecases#files_bucket)] | Adds a new domain layer that uses UseCases for business logic. |
+
+### Old samples - Kotlin and Java
+
+Blueprints v1 had a collection of samples that are not maintained anymore, but can still be useful. See [all project branches](https://github.com/googlesamples/android-architecture/branches).
+
+## Why a to-do app?
+
+<img align="right" src="https://github.com/googlesamples/android-architecture/wiki/images/todoapp.gif" alt="A demo illustraating the UI of the app" width="288" height="512" style="display: inline; float: right"/>
+
+The app in this project aims to be simple enough that you can understand it quickly, but complex enough to showcase difficult design decisions and testing scenarios. For more information, see the [app's specification](https://github.com/googlesamples/android-architecture/wiki/To-do-app-specification).
+
+## What is it not?
+
+*   A UI/Material Design sample. The interface of the app is deliberately kept simple to focus on architecture. Check out [Plaid](https://github.com/android/plaid) instead.
+*   A complete Jetpack sample covering all libraries. Check out [Android Sunflower](https://github.com/googlesamples/android-sunflower) or the advanced [Github Browser Sample](https://github.com/googlesamples/android-architecture-components/tree/master/GithubBrowserSample) instead.
+*   A real production app with network access, user authentication, etc. Check out the [Google I/O app](https://github.com/google/iosched), [Santa Tracker](https://github.com/google/santa-tracker-android) or [Tivi](https://github.com/chrisbanes/tivi) for that.
+
+## Who is it for?
+
+*   Intermediate developers and beginners looking for a way to structure their app in a testable and maintainable way.
+*   Advanced developers looking for quick reference.
+
+## Opening a sample in Android Studio
+
+To open one of the samples in Android Studio, begin by checking out one of the sample branches, and then open the root directory in Android Studio. The following series of steps illustrate how to open the [usecases](tree/usecases/) sample.
+
+Clone the repository:
+
+```
+git clone git@github.com:googlesamples/android-architecture.git
+```
+This step checks out the master branch. If you want to change to a different sample: 
+
+```
+git checkout usecases
+```
+
+**Note:** To review a different sample, replace `usecases` with the name of sample you want to check out.
+
+Finally open the `android-architecture/` directory in Android Studio.
+
+### License
+
+
+```
+Copyright 2019 Google, Inc.
+
+Licensed to the Apache Software Foundation (ASF) under one or more contributor
+license agreements. See the NOTICE file distributed with this work for
+additional information regarding copyright ownership. The ASF licenses this
+file to you under the Apache License, Version 2.0 (the "License"); you may not
+use this file except in compliance with the License. You may obtain a copy of
+the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+License for the specific language governing permissions and limitations under
+the License.
+```
--- a/app/.gitignore
+++ b/app/.gitignore
+/build
--- a/app/build.gradle
+++ b/app/build.gradle
+apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-kapt'
+apply plugin: "androidx.navigation.safeargs.kotlin"
+
+android {
+    compileSdkVersion rootProject.compileSdkVersion
+
+    defaultConfig {
+        applicationId "com.example.android.architecture.blueprints.master"
+        minSdkVersion rootProject.minSdkVersion
+        targetSdkVersion rootProject.targetSdkVersion
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner 'androidx.test.runner.AndroidJUnitRunner'
+    }
+
+    android {
+        sourceSets {
+            String sharedTestDir = 'src/sharedTest/java'
+            test {
+                java.srcDirs += sharedTestDir
+            }
+            androidTest {
+                java.srcDirs += sharedTestDir
+            }
+        }
+    }
+
+    buildTypes {
+        debug {
+            minifyEnabled false
+            testCoverageEnabled true
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+            testProguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguardTest-rules.pro'
+        }
+
+        release {
+            minifyEnabled true
+            shrinkResources true
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+            testProguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguardTest-rules.pro'
+        }
+    }
+
+    flavorDimensions "default"
+
+    // If you need to add more flavors, consider using flavor dimensions.
+    productFlavors {
+        mock {
+            dimension "default"
+            applicationIdSuffix = ".mock"
+        }
+        prod {
+            dimension "default"
+        }
+    }
+
+    // Remove mockRelease as it's not needed.
+    android.variantFilter { variant ->
+        if (variant.buildType.name == 'release'
+                && variant.getFlavors().get(0).name == 'mock') {
+            variant.setIgnore(true)
+        }
+    }
+
+    // Always show the result of every unit test, even if it passes.
+    testOptions.unitTests {
+        includeAndroidResources = true
+
+        all {
+            testLogging {
+                events 'passed', 'skipped', 'failed', 'standardOut', 'standardError'
+            }
+        }
+    }
+
+    dataBinding {
+        enabled = true
+        enabledForTests = true
+    }
+
+    compileOptions {
+        sourceCompatibility = 1.8
+        targetCompatibility = 1.8
+    }
+
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+}
+
+/*
+ Dependency versions are defined in the top level build.gradle file. This helps keeping track of
+ all versions in a single place. This improves readability and helps managing project complexity.
+ */
+dependencies {
+
+    // App dependencies
+    implementation "androidx.appcompat:appcompat:$appCompatVersion"
+    implementation "androidx.cardview:cardview:$cardVersion"
+    implementation "com.google.android.material:material:$materialVersion"
+    implementation "androidx.recyclerview:recyclerview:$recyclerViewVersion"
+    implementation "androidx.annotation:annotation:$androidXAnnotations"
+    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$coroutinesVersion"
+    implementation "com.jakewharton.timber:timber:$timberVersion"
+    implementation "androidx.legacy:legacy-support-v4:$androidXLegacySupport"
+    implementation "androidx.test.espresso:espresso-idling-resource:$espressoVersion"
+    implementation "androidx.room:room-runtime:$roomVersion"
+    kapt "androidx.room:room-compiler:$roomVersion"
+
+    // Architecture Components
+    implementation "androidx.room:room-runtime:$roomVersion"
+    kapt "androidx.room:room-compiler:$roomVersion"
+    implementation "androidx.room:room-ktx:$roomVersion"
+    implementation "androidx.lifecycle:lifecycle-extensions:$archLifecycleVersion"
+    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$archLifecycleVersion"
+    implementation "androidx.lifecycle:lifecycle-livedata-ktx:$archLifecycleVersion"
+    implementation "androidx.navigation:navigation-fragment-ktx:$navigationVersion"
+    implementation "androidx.navigation:navigation-ui-ktx:$navigationVersion"
+
+    // Dependencies for local unit tests
+    testImplementation "junit:junit:$junitVersion"
+    testImplementation "org.mockito:mockito-core:$mockitoVersion"
+    testImplementation "org.hamcrest:hamcrest-all:$hamcrestVersion"
+    testImplementation "androidx.arch.core:core-testing:$archTestingVersion"
+    testImplementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$coroutinesVersion"
+    testImplementation "org.jetbrains.kotlinx:kotlinx-coroutines-test:$coroutinesVersion"
+    testImplementation "org.robolectric:robolectric:$robolectricVersion"
+    testImplementation "androidx.test.espresso:espresso-core:$espressoVersion"
+    testImplementation "androidx.test.espresso:espresso-contrib:$espressoVersion"
+    testImplementation "androidx.test.espresso:espresso-intents:$espressoVersion"
+    testImplementation "com.google.truth:truth:$truthVersion"
+
+    // Dependencies for Android unit tests
+    androidTestImplementation "junit:junit:$junitVersion"
+    androidTestImplementation "org.mockito:mockito-core:$mockitoVersion"
+    androidTestImplementation "com.linkedin.dexmaker:dexmaker-mockito:$dexMakerVersion"
+    androidTestImplementation "org.jetbrains.kotlinx:kotlinx-coroutines-test:$coroutinesVersion"
+
+    // AndroidX Test - JVM testing
+    testImplementation "androidx.test:core-ktx:$androidXTestCoreVersion"
+    testImplementation "androidx.test.ext:junit-ktx:$androidXTestExtKotlinRunnerVersion"
+    testImplementation "androidx.test:rules:$androidXTestRulesVersion"
+    // Once https://issuetracker.google.com/127986458 is fixed this can be testImplementation
+    implementation "androidx.fragment:fragment-testing:$fragmentVersion"
+    implementation "androidx.test:core:$androidXTestCoreVersion"
+    implementation "androidx.fragment:fragment:$fragmentVersion"
+
+    // AndroidX Test - Instrumented testing
+    androidTestImplementation "androidx.test:core-ktx:$androidXTestCoreVersion"
+    androidTestImplementation "androidx.test.ext:junit-ktx:$androidXTestExtKotlinRunnerVersion"
+    androidTestImplementation "androidx.test:rules:$androidXTestRulesVersion"
+    androidTestImplementation "androidx.room:room-testing:$roomVersion"
+    androidTestImplementation "androidx.arch.core:core-testing:$archTestingVersion"
+    androidTestImplementation "androidx.test.espresso:espresso-core:$espressoVersion"
+    androidTestImplementation "androidx.test.espresso:espresso-contrib:$espressoVersion"
+    androidTestImplementation "androidx.test.espresso:espresso-intents:$espressoVersion"
+    androidTestImplementation "androidx.test.espresso.idling:idling-concurrent:$espressoVersion"
+    androidTestImplementation "org.robolectric:annotations:$robolectricVersion"
+    implementation "androidx.test.espresso:espresso-idling-resource:$espressoVersion"
+
+    // Resolve conflicts between main and test APK:
+    androidTestImplementation "androidx.annotation:annotation:$androidXAnnotations"
+    androidTestImplementation "androidx.legacy:legacy-support-v4:$androidXLegacySupport"
+    androidTestImplementation "androidx.recyclerview:recyclerview:$recyclerViewVersion"
+    androidTestImplementation "androidx.appcompat:appcompat:$appCompatVersion"
+    androidTestImplementation "com.google.android.material:material:$materialVersion"
+
+    // Kotlin
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlinVersion"
+    implementation "androidx.fragment:fragment-ktx:$fragmentKtxVersion"
+}
--- a/app/proguard-rules.pro
+++ b/app/proguard-rules.pro
+-dontoptimize
+
+# Some methods are only called from tests, so make sure the shrinker keeps them.
+-keep class com.example.android.architecture.blueprints.** { *; }
+
+-keep class androidx.drawerlayout.widget.DrawerLayout { *; }
+-keep class androidx.test.espresso.**
+# keep the class and specified members from being removed or renamed
+-keep class androidx.test.espresso.IdlingRegistry { *; }
+-keep class androidx.test.espresso.IdlingResource { *; }
+
+-keep class com.google.common.base.Preconditions { *; }
+
+-keep class androidx.room.RoomDataBase { *; }
+-keep class androidx.room.Room { *; }
+-keep class android.arch.** { *; }
+
+# Proguard rules that are applied to your test apk/code.
+-ignorewarnings
+
+-keepattributes *Annotation*
+
+-dontnote junit.framework.**
+-dontnote junit.runner.**
+
+-dontwarn androidx.test.**
+-dontwarn org.junit.**
+-dontwarn org.hamcrest.**
+-dontwarn com.squareup.javawriter.JavaWriter
+# Uncomment this if you use Mockito
+-dontwarn org.mockito.**
--- a/app/proguardTest-rules.pro
+++ b/app/proguardTest-rules.pro
+# Proguard rules that are applied to your test apk/code.
+-ignorewarnings
+-dontoptimize
+
+-keepattributes *Annotation*
+
+-keep class androidx.test.espresso.**
+# keep the class and specified members from being removed or renamed
+-keep class androidx.test.espresso.IdlingRegistry { *; }
+-keep class androidx.test.espresso.IdlingResource { *; }
+
+-dontnote junit.framework.**
+-dontnote junit.runner.**
+
+-dontwarn androidx.test.**
+-dontwarn org.junit.**
+-dontwarn org.hamcrest.**
+-dontwarn com.squareup.javawriter.JavaWriter
+# Uncomment this if you use Mockito
+-dontwarn org.mockito.**
\ No newline at end of file
--- a/app/src/androidTestMock/java/com/example/android/architecture/blueprints/todoapp/tasks/AppNavigationTest.kt
+++ b/app/src/androidTestMock/java/com/example/android/architecture/blueprints/todoapp/tasks/AppNavigationTest.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.tasks
+
+import android.view.Gravity
+import androidx.drawerlayout.widget.DrawerLayout
+import androidx.navigation.findNavController
+import androidx.test.core.app.ActivityScenario
+import androidx.test.core.app.ApplicationProvider.getApplicationContext
+import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.Espresso.pressBack
+import androidx.test.espresso.IdlingRegistry
+import androidx.test.espresso.action.ViewActions.click
+import androidx.test.espresso.assertion.ViewAssertions.matches
+import androidx.test.espresso.contrib.DrawerActions.open
+import androidx.test.espresso.contrib.DrawerMatchers.isClosed
+import androidx.test.espresso.contrib.DrawerMatchers.isOpen
+import androidx.test.espresso.contrib.NavigationViewActions.navigateTo
+import androidx.test.espresso.matcher.ViewMatchers.isDisplayed
+import androidx.test.espresso.matcher.ViewMatchers.withContentDescription
+import androidx.test.espresso.matcher.ViewMatchers.withId
+import androidx.test.espresso.matcher.ViewMatchers.withText
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.filters.LargeTest
+import com.example.android.architecture.blueprints.todoapp.R
+import com.example.android.architecture.blueprints.todoapp.ServiceLocator
+import com.example.android.architecture.blueprints.todoapp.data.Task
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksRepository
+import com.example.android.architecture.blueprints.todoapp.util.DataBindingIdlingResource
+import com.example.android.architecture.blueprints.todoapp.util.EspressoIdlingResource
+import com.example.android.architecture.blueprints.todoapp.util.monitorActivity
+import com.example.android.architecture.blueprints.todoapp.util.saveTaskBlocking
+import org.junit.After
+import org.junit.Before
+import org.junit.Test
+import org.junit.runner.RunWith
+
+/**
+ * Tests for the [DrawerLayout] layout component in [TasksActivity] which manages
+ * navigation within the app.
+ *
+ * UI tests usually use [ActivityTestRule] but there's no API to perform an action before
+ * each test. The workaround is to use `ActivityScenario.launch()` and `ActivityScenario.close()`.
+ */
+@RunWith(AndroidJUnit4::class)
+@LargeTest
+class AppNavigationTest {
+
+    private lateinit var tasksRepository: TasksRepository
+
+    // An Idling Resource that waits for Data Binding to have no pending bindings
+    private val dataBindingIdlingResource = DataBindingIdlingResource()
+
+    @Before
+    fun init() {
+        tasksRepository = ServiceLocator.provideTasksRepository(getApplicationContext())
+    }
+
+    @After
+    fun reset() {
+        ServiceLocator.resetRepository()
+    }
+
+    /**
+     * Idling resources tell Espresso that the app is idle or busy. This is needed when operations
+     * are not scheduled in the main Looper (for example when executed on a different thread).
+     */
+    @Before
+    fun registerIdlingResource() {
+        IdlingRegistry.getInstance().register(EspressoIdlingResource.countingIdlingResource)
+        IdlingRegistry.getInstance().register(dataBindingIdlingResource)
+    }
+
+    /**
+     * Unregister your Idling Resource so it can be garbage collected and does not leak any memory.
+     */
+    @After
+    fun unregisterIdlingResource() {
+        IdlingRegistry.getInstance().unregister(EspressoIdlingResource.countingIdlingResource)
+        IdlingRegistry.getInstance().unregister(dataBindingIdlingResource)
+    }
+
+    @Test
+    fun drawerNavigationFromTasksToStatistics() {
+        // start up Tasks screen
+        val activityScenario = ActivityScenario.launch(TasksActivity::class.java)
+        dataBindingIdlingResource.monitorActivity(activityScenario)
+
+        onView(withId(R.id.drawer_layout))
+            .check(matches(isClosed(Gravity.START))) // Left Drawer should be closed.
+            .perform(open()) // Open Drawer
+
+        // Start statistics screen.
+        onView(withId(R.id.nav_view))
+            .perform(navigateTo(R.id.statistics_fragment_dest))
+
+        // Check that statistics screen was opened.
+        onView(withId(R.id.statistics_layout)).check(matches(isDisplayed()))
+
+        onView(withId(R.id.drawer_layout))
+            .check(matches(isClosed(Gravity.START))) // Left Drawer should be closed.
+            .perform(open()) // Open Drawer
+
+        // Start tasks screen.
+        onView(withId(R.id.nav_view))
+            .perform(navigateTo(R.id.tasks_fragment_dest))
+
+        // Check that tasks screen was opened.
+        onView(withId(R.id.tasks_container_layout)).check(matches(isDisplayed()))
+        // When using ActivityScenario.launch, always call close()
+        activityScenario.close()
+    }
+
+    @Test
+    fun tasksScreen_clickOnAndroidHomeIcon_OpensNavigation() {
+        // start up Tasks screen
+        val activityScenario = ActivityScenario.launch(TasksActivity::class.java)
+        dataBindingIdlingResource.monitorActivity(activityScenario)
+
+        // Check that left drawer is closed at startup
+        onView(withId(R.id.drawer_layout))
+            .check(matches(isClosed(Gravity.START))) // Left Drawer should be closed.
+
+        // Open Drawer
+        onView(
+            withContentDescription(
+                activityScenario
+                    .getToolbarNavigationContentDescription()
+            )
+        ).perform(click())
+
+        // Check if drawer is open
+        onView(withId(R.id.drawer_layout))
+            .check(matches(isOpen(Gravity.START))) // Left drawer is open open.
+        // When using ActivityScenario.launch, always call close()
+        activityScenario.close()
+    }
+
+    @Test
+    fun statsScreen_clickOnAndroidHomeIcon_OpensNavigation() {
+        // start up Tasks screen
+        val activityScenario = ActivityScenario.launch(TasksActivity::class.java)
+        dataBindingIdlingResource.monitorActivity(activityScenario)
+
+        // When the user navigates to the stats screen
+        activityScenario.onActivity {
+            it.findNavController(R.id.nav_host_fragment).navigate(R.id.statistics_fragment_dest)
+        }
+
+        // Then check that left drawer is closed at startup
+        onView(withId(R.id.drawer_layout))
+            .check(matches(isClosed(Gravity.START))) // Left Drawer should be closed.
+
+        // When the drawer is opened
+        onView(
+            withContentDescription(
+                activityScenario
+                    .getToolbarNavigationContentDescription()
+            )
+        ).perform(click())
+
+        // Then check that the drawer is open
+        onView(withId(R.id.drawer_layout))
+            .check(matches(isOpen(Gravity.START))) // Left drawer is open open.
+        // When using ActivityScenario.launch, always call close()
+        activityScenario.close()
+    }
+
+    @Test
+    fun taskDetailScreen_doubleUIBackButton() {
+        val task = Task("UI <- button", "Description")
+        tasksRepository.saveTaskBlocking(task)
+
+        // start up Tasks screen
+        val activityScenario = ActivityScenario.launch(TasksActivity::class.java)
+        dataBindingIdlingResource.monitorActivity(activityScenario)
+
+        // Click on the task on the list
+        onView(withText("UI <- button")).perform(click())
+        // Click on the edit task button
+        onView(withId(R.id.edit_task_fab)).perform(click())
+
+        // Confirm that if we click "<-" once, we end up back at the task details page
+        onView(
+            withContentDescription(
+                activityScenario
+                    .getToolbarNavigationContentDescription()
+            )
+        ).perform(click())
+        onView(withId(R.id.task_detail_title_text)).check(matches(isDisplayed()))
+
+        // Confirm that if we click "<-" a second time, we end up back at the home screen
+        onView(
+            withContentDescription(
+                activityScenario
+                    .getToolbarNavigationContentDescription()
+            )
+        ).perform(click())
+        onView(withId(R.id.tasks_container_layout)).check(matches(isDisplayed()))
+        // When using ActivityScenario.launch, always call close()
+        activityScenario.close()
+    }
+
+    @Test
+    fun taskDetailScreen_doubleBackButton() {
+        val task = Task("Back button", "Description")
+        tasksRepository.saveTaskBlocking(task)
+
+        // start up Tasks screen
+        val activityScenario = ActivityScenario.launch(TasksActivity::class.java)
+        dataBindingIdlingResource.monitorActivity(activityScenario)
+
+        // Click on the task on the list
+        onView(withText("Back button")).perform(click())
+        // Click on the edit task button
+        onView(withId(R.id.edit_task_fab)).perform(click())
+
+        // Confirm that if we click back once, we end up back at the task details page
+        pressBack()
+        onView(withId(R.id.task_detail_title_text)).check(matches(isDisplayed()))
+
+        // Confirm that if we click back a second time, we end up back at the home screen
+        pressBack()
+        onView(withId(R.id.tasks_container_layout)).check(matches(isDisplayed()))
+        // When using ActivityScenario.launch, always call close()
+        activityScenario.close()
+    }
+}
--- a/app/src/androidTestMock/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksActivityTest.kt
+++ b/app/src/androidTestMock/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksActivityTest.kt
--- a/app/src/androidTestMock/java/com/example/android/architecture/blueprints/todoapp/tasks/TestUtils.kt
+++ b/app/src/androidTestMock/java/com/example/android/architecture/blueprints/todoapp/tasks/TestUtils.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.architecture.blueprints.todoapp.tasks
+
+import android.app.Activity
+import androidx.appcompat.widget.Toolbar
+import androidx.test.core.app.ActivityScenario
+import com.example.android.architecture.blueprints.todoapp.R
+
+fun <T : Activity> ActivityScenario<T>.getToolbarNavigationContentDescription(): String {
+    var description = ""
+    onActivity {
+        description =
+            it.findViewById<Toolbar>(R.id.toolbar).navigationContentDescription as String
+    }
+    return description
+}
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.example.android.architecture.blueprints.todoapp">
+
+    <application
+        android:allowBackup="false"
+        android:name=".TodoApplication"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:supportsRtl="true"
+        android:theme="@style/AppTheme">
+        <activity
+            android:name="com.example.android.architecture.blueprints.todoapp.tasks.TasksActivity"
+            android:windowSoftInputMode="adjustResize"
+            android:theme="@style/AppTheme.OverlapSystemBar">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/Event.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/Event.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp
+
+import androidx.lifecycle.Observer
+
+/**
+ * Used as a wrapper for data that is exposed via a LiveData that represents an event.
+ */
+open class Event<out T>(private val content: T) {
+
+    @Suppress("MemberVisibilityCanBePrivate")
+    var hasBeenHandled = false
+        private set // Allow external read but not write
+
+    /**
+     * Returns the content and prevents its use again.
+     */
+    fun getContentIfNotHandled(): T? {
+        return if (hasBeenHandled) {
+            null
+        } else {
+            hasBeenHandled = true
+            content
+        }
+    }
+
+    /**
+     * Returns the content, even if it's already been handled.
+     */
+    fun peekContent(): T = content
+}
+
+/**
+ * An [Observer] for [Event]s, simplifying the pattern of checking if the [Event]'s content has
+ * already been handled.
+ *
+ * [onEventUnhandledContent] is *only* called if the [Event]'s contents has not been handled.
+ */
+class EventObserver<T>(private val onEventUnhandledContent: (T) -> Unit) : Observer<Event<T>> {
+    override fun onChanged(event: Event<T>?) {
+        event?.getContentIfNotHandled()?.let {
+            onEventUnhandledContent(it)
+        }
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/ScrollChildSwipeRefreshLayout.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/ScrollChildSwipeRefreshLayout.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp
+
+import android.content.Context
+import android.util.AttributeSet
+import android.view.View
+import androidx.swiperefreshlayout.widget.SwipeRefreshLayout
+
+/**
+ * Extends [SwipeRefreshLayout] to support non-direct descendant scrolling views.
+ *
+ *
+ * [SwipeRefreshLayout] works as expected when a scroll view is a direct child: it triggers
+ * the refresh only when the view is on top. This class adds a way (@link #setScrollUpChild} to
+ * define which view controls this behavior.
+ */
+class ScrollChildSwipeRefreshLayout @JvmOverloads constructor(
+    context: Context,
+    attrs: AttributeSet? = null
+) : SwipeRefreshLayout(context, attrs) {
+
+    var scrollUpChild: View? = null
+
+    override fun canChildScrollUp() =
+        scrollUpChild?.canScrollVertically(-1) ?: super.canChildScrollUp()
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/TodoApplication.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/TodoApplication.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.architecture.blueprints.todoapp
+
+import android.app.Application
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksRepository
+import timber.log.Timber
+import timber.log.Timber.DebugTree
+
+/**
+ * An application that lazily provides a repository. Note that this Service Locator pattern is
+ * used to simplify the sample. Consider a Dependency Injection framework.
+ *
+ * Also, sets up Timber in the DEBUG BuildConfig. Read Timber's documentation for production setups.
+ */
+class TodoApplication : Application() {
+
+    // Depends on the flavor,
+    val taskRepository: TasksRepository
+        get() = ServiceLocator.provideTasksRepository(this)
+
+    override fun onCreate() {
+        super.onCreate()
+        if (BuildConfig.DEBUG) Timber.plant(DebugTree())
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/ViewModelFactory.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/ViewModelFactory.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp
+
+import android.app.Application
+import android.os.Bundle
+import androidx.lifecycle.AbstractSavedStateViewModelFactory
+import androidx.lifecycle.SavedStateHandle
+import androidx.lifecycle.SavedStateViewModelFactory
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
+import androidx.savedstate.SavedStateRegistryOwner
+import com.example.android.architecture.blueprints.todoapp.addedittask.AddEditTaskViewModel
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksRepository
+import com.example.android.architecture.blueprints.todoapp.statistics.StatisticsViewModel
+import com.example.android.architecture.blueprints.todoapp.taskdetail.TaskDetailViewModel
+import com.example.android.architecture.blueprints.todoapp.tasks.TasksViewModel
+
+/**
+ * Factory for all ViewModels.
+ */
+@Suppress("UNCHECKED_CAST")
+class ViewModelFactory constructor(
+        private val tasksRepository: TasksRepository,
+        owner: SavedStateRegistryOwner,
+        defaultArgs: Bundle? = null
+) : AbstractSavedStateViewModelFactory(owner, defaultArgs) {
+
+    override fun <T : ViewModel> create(
+            key: String,
+            modelClass: Class<T>,
+            handle: SavedStateHandle
+    ) = with(modelClass) {
+        when {
+            isAssignableFrom(StatisticsViewModel::class.java) ->
+                StatisticsViewModel(tasksRepository)
+            isAssignableFrom(TaskDetailViewModel::class.java) ->
+                TaskDetailViewModel(tasksRepository)
+            isAssignableFrom(AddEditTaskViewModel::class.java) ->
+                AddEditTaskViewModel(tasksRepository)
+            isAssignableFrom(TasksViewModel::class.java) ->
+                TasksViewModel(tasksRepository, handle)
+            else ->
+                throw IllegalArgumentException("Unknown ViewModel class: ${modelClass.name}")
+        }
+    } as T
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/addedittask/AddEditTaskFragment.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/addedittask/AddEditTaskFragment.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.addedittask
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.viewModels
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.fragment.navArgs
+import com.example.android.architecture.blueprints.todoapp.EventObserver
+import com.example.android.architecture.blueprints.todoapp.R
+import com.example.android.architecture.blueprints.todoapp.databinding.AddtaskFragBinding
+import com.example.android.architecture.blueprints.todoapp.tasks.ADD_EDIT_RESULT_OK
+import com.example.android.architecture.blueprints.todoapp.util.getViewModelFactory
+import com.example.android.architecture.blueprints.todoapp.util.setupRefreshLayout
+import com.example.android.architecture.blueprints.todoapp.util.setupSnackbar
+import com.google.android.material.snackbar.Snackbar
+
+/**
+ * Main UI for the add task screen. Users can enter a task title and description.
+ */
+class AddEditTaskFragment : Fragment() {
+
+    private lateinit var viewDataBinding: AddtaskFragBinding
+
+    private val args: AddEditTaskFragmentArgs by navArgs()
+
+    private val viewModel by viewModels<AddEditTaskViewModel> { getViewModelFactory() }
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        val root = inflater.inflate(R.layout.addtask_frag, container, false)
+        viewDataBinding = AddtaskFragBinding.bind(root).apply {
+            this.viewmodel = viewModel
+        }
+        // Set the lifecycle owner to the lifecycle of the view
+        viewDataBinding.lifecycleOwner = this.viewLifecycleOwner
+        return viewDataBinding.root
+    }
+
+    override fun onActivityCreated(savedInstanceState: Bundle?) {
+        super.onActivityCreated(savedInstanceState)
+        setupSnackbar()
+        setupNavigation()
+        this.setupRefreshLayout(viewDataBinding.refreshLayout)
+        viewModel.start(args.taskId)
+    }
+
+    private fun setupSnackbar() {
+        view?.setupSnackbar(this, viewModel.snackbarText, Snackbar.LENGTH_SHORT)
+    }
+
+    private fun setupNavigation() {
+        viewModel.taskUpdatedEvent.observe(this, EventObserver {
+            val action = AddEditTaskFragmentDirections
+                .actionAddEditTaskFragmentToTasksFragment(ADD_EDIT_RESULT_OK)
+            findNavController().navigate(action)
+        })
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/addedittask/AddEditTaskViewModel.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/addedittask/AddEditTaskViewModel.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.architecture.blueprints.todoapp.addedittask
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.example.android.architecture.blueprints.todoapp.Event
+import com.example.android.architecture.blueprints.todoapp.R
+import com.example.android.architecture.blueprints.todoapp.data.Result.Success
+import com.example.android.architecture.blueprints.todoapp.data.Task
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksRepository
+import kotlinx.coroutines.launch
+
+/**
+ * ViewModel for the Add/Edit screen.
+ */
+class AddEditTaskViewModel(
+    private val tasksRepository: TasksRepository
+) : ViewModel() {
+
+    // Two-way databinding, exposing MutableLiveData
+    val title = MutableLiveData<String>()
+
+    // Two-way databinding, exposing MutableLiveData
+    val description = MutableLiveData<String>()
+
+    private val _dataLoading = MutableLiveData<Boolean>()
+    val dataLoading: LiveData<Boolean> = _dataLoading
+
+    private val _snackbarText = MutableLiveData<Event<Int>>()
+    val snackbarText: LiveData<Event<Int>> = _snackbarText
+
+    private val _taskUpdatedEvent = MutableLiveData<Event<Unit>>()
+    val taskUpdatedEvent: LiveData<Event<Unit>> = _taskUpdatedEvent
+
+    private var taskId: String? = null
+
+    private var isNewTask: Boolean = false
+
+    private var isDataLoaded = false
+
+    private var taskCompleted = false
+
+    fun start(taskId: String?) {
+        if (_dataLoading.value == true) {
+            return
+        }
+
+        this.taskId = taskId
+        if (taskId == null) {
+            // No need to populate, it's a new task
+            isNewTask = true
+            return
+        }
+        if (isDataLoaded) {
+            // No need to populate, already have data.
+            return
+        }
+
+        isNewTask = false
+        _dataLoading.value = true
+
+        viewModelScope.launch {
+            tasksRepository.getTask(taskId).let { result ->
+                if (result is Success) {
+                    onTaskLoaded(result.data)
+                } else {
+                    onDataNotAvailable()
+                }
+            }
+        }
+    }
+
+    private fun onTaskLoaded(task: Task) {
+        title.value = task.title
+        description.value = task.description
+        taskCompleted = task.isCompleted
+        _dataLoading.value = false
+        isDataLoaded = true
+    }
+
+    private fun onDataNotAvailable() {
+        _dataLoading.value = false
+    }
+
+    // Called when clicking on fab.
+    fun saveTask() {
+        val currentTitle = title.value
+        val currentDescription = description.value
+
+        if (currentTitle == null || currentDescription == null) {
+            _snackbarText.value = Event(R.string.empty_task_message)
+            return
+        }
+        if (Task(currentTitle, currentDescription).isEmpty) {
+            _snackbarText.value = Event(R.string.empty_task_message)
+            return
+        }
+
+        val currentTaskId = taskId
+        if (isNewTask || currentTaskId == null) {
+            createTask(Task(currentTitle, currentDescription))
+        } else {
+            val task = Task(currentTitle, currentDescription, taskCompleted, currentTaskId)
+            updateTask(task)
+        }
+    }
+
+    private fun createTask(newTask: Task) = viewModelScope.launch {
+        tasksRepository.saveTask(newTask)
+        _taskUpdatedEvent.value = Event(Unit)
+    }
+
+    private fun updateTask(task: Task) {
+        if (isNewTask) {
+            throw RuntimeException("updateTask() was called but task is new.")
+        }
+        viewModelScope.launch {
+            tasksRepository.saveTask(task)
+            _taskUpdatedEvent.value = Event(Unit)
+        }
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/Result.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/Result.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.architecture.blueprints.todoapp.data
+
+import com.example.android.architecture.blueprints.todoapp.data.Result.Success
+
+/**
+ * A generic class that holds a value with its loading status.
+ * @param <T>
+ */
+sealed class Result<out R> {
+
+    data class Success<out T>(val data: T) : Result<T>()
+    data class Error(val exception: Exception) : Result<Nothing>()
+    object Loading : Result<Nothing>()
+
+    override fun toString(): String {
+        return when (this) {
+            is Success<*> -> "Success[data=$data]"
+            is Error -> "Error[exception=$exception]"
+            Loading -> "Loading"
+        }
+    }
+}
+
+/**
+ * `true` if [Result] is of type [Success] & holds non-null [Success.data].
+ */
+val Result<*>.succeeded
+    get() = this is Success && data != null
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/Task.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/Task.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.data
+
+import androidx.room.ColumnInfo
+import androidx.room.Entity
+import androidx.room.PrimaryKey
+import java.util.UUID
+
+/**
+ * Immutable model class for a Task. In order to compile with Room, we can't use @JvmOverloads to
+ * generate multiple constructors.
+ *
+ * @param title title of the task
+ * @param description description of the task
+ * @param isCompleted whether or not this task is completed
+ * @param id id of the task
+ */
+@Entity(tableName = "tasks")
+data class Task @JvmOverloads constructor(
+    @ColumnInfo(name = "title") var title: String = "",
+    @ColumnInfo(name = "description") var description: String = "",
+    @ColumnInfo(name = "completed") var isCompleted: Boolean = false,
+    @PrimaryKey @ColumnInfo(name = "entryid") var id: String = UUID.randomUUID().toString()
+) {
+
+    val titleForList: String
+        get() = if (title.isNotEmpty()) title else description
+
+    val isActive
+        get() = !isCompleted
+
+    val isEmpty
+        get() = title.isEmpty() || description.isEmpty()
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/source/DefaultTasksRepository.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/source/DefaultTasksRepository.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.data.source
+
+import androidx.lifecycle.LiveData
+import com.example.android.architecture.blueprints.todoapp.data.Result
+import com.example.android.architecture.blueprints.todoapp.data.Result.Success
+import com.example.android.architecture.blueprints.todoapp.data.Task
+import com.example.android.architecture.blueprints.todoapp.util.wrapEspressoIdlingResource
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.coroutineScope
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+
+/**
+ * Default implementation of [TasksRepository]. Single entry point for managing tasks' data.
+ */
+class DefaultTasksRepository(
+    private val tasksRemoteDataSource: TasksDataSource,
+    private val tasksLocalDataSource: TasksDataSource,
+    private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
+) : TasksRepository {
+
+    override suspend fun getTasks(forceUpdate: Boolean): Result<List<Task>> {
+        // Set app as busy while this function executes.
+        wrapEspressoIdlingResource {
+
+            if (forceUpdate) {
+                try {
+                    updateTasksFromRemoteDataSource()
+                } catch (ex: Exception) {
+                    return Result.Error(ex)
+                }
+            }
+            return tasksLocalDataSource.getTasks()
+        }
+    }
+
+    override suspend fun refreshTasks() {
+        updateTasksFromRemoteDataSource()
+    }
+
+    override fun observeTasks(): LiveData<Result<List<Task>>> {
+        return tasksLocalDataSource.observeTasks()
+    }
+
+    override suspend fun refreshTask(taskId: String) {
+        updateTaskFromRemoteDataSource(taskId)
+    }
+
+    private suspend fun updateTasksFromRemoteDataSource() {
+        val remoteTasks = tasksRemoteDataSource.getTasks()
+
+        if (remoteTasks is Success) {
+            // Real apps might want to do a proper sync, deleting, modifying or adding each task.
+            tasksLocalDataSource.deleteAllTasks()
+            remoteTasks.data.forEach { task ->
+                tasksLocalDataSource.saveTask(task)
+            }
+        } else if (remoteTasks is Result.Error) {
+            throw remoteTasks.exception
+        }
+    }
+
+    override fun observeTask(taskId: String): LiveData<Result<Task>> {
+        return tasksLocalDataSource.observeTask(taskId)
+    }
+
+    private suspend fun updateTaskFromRemoteDataSource(taskId: String) {
+        val remoteTask = tasksRemoteDataSource.getTask(taskId)
+
+        if (remoteTask is Success) {
+            tasksLocalDataSource.saveTask(remoteTask.data)
+        }
+    }
+
+    /**
+     * Relies on [getTasks] to fetch data and picks the task with the same ID.
+     */
+    override suspend fun getTask(taskId: String, forceUpdate: Boolean): Result<Task> {
+        // Set app as busy while this function executes.
+        wrapEspressoIdlingResource {
+            if (forceUpdate) {
+                updateTaskFromRemoteDataSource(taskId)
+            }
+            return tasksLocalDataSource.getTask(taskId)
+        }
+    }
+
+    override suspend fun saveTask(task: Task) {
+        coroutineScope {
+            launch { tasksRemoteDataSource.saveTask(task) }
+            launch { tasksLocalDataSource.saveTask(task) }
+        }
+    }
+
+    override suspend fun completeTask(task: Task) {
+        coroutineScope {
+            launch { tasksRemoteDataSource.completeTask(task) }
+            launch { tasksLocalDataSource.completeTask(task) }
+        }
+    }
+
+    override suspend fun completeTask(taskId: String) {
+        withContext(ioDispatcher) {
+            (getTaskWithId(taskId) as? Success)?.let { it ->
+                completeTask(it.data)
+            }
+        }
+    }
+
+    override suspend fun activateTask(task: Task) = withContext<Unit>(ioDispatcher) {
+        coroutineScope {
+            launch { tasksRemoteDataSource.activateTask(task) }
+            launch { tasksLocalDataSource.activateTask(task) }
+        }
+    }
+
+    override suspend fun activateTask(taskId: String) {
+        withContext(ioDispatcher) {
+            (getTaskWithId(taskId) as? Success)?.let { it ->
+                activateTask(it.data)
+            }
+        }
+    }
+
+    override suspend fun clearCompletedTasks() {
+        coroutineScope {
+            launch { tasksRemoteDataSource.clearCompletedTasks() }
+            launch { tasksLocalDataSource.clearCompletedTasks() }
+        }
+    }
+
+    override suspend fun deleteAllTasks() {
+        withContext(ioDispatcher) {
+            coroutineScope {
+                launch { tasksRemoteDataSource.deleteAllTasks() }
+                launch { tasksLocalDataSource.deleteAllTasks() }
+            }
+        }
+    }
+
+    override suspend fun deleteTask(taskId: String) {
+        coroutineScope {
+            launch { tasksRemoteDataSource.deleteTask(taskId) }
+            launch { tasksLocalDataSource.deleteTask(taskId) }
+        }
+    }
+
+    private suspend fun getTaskWithId(id: String): Result<Task> {
+        return tasksLocalDataSource.getTask(id)
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/source/TasksDataSource.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/source/TasksDataSource.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.data.source
+
+import androidx.lifecycle.LiveData
+import com.example.android.architecture.blueprints.todoapp.data.Result
+import com.example.android.architecture.blueprints.todoapp.data.Task
+
+/**
+ * Main entry point for accessing tasks data.
+ */
+interface TasksDataSource {
+
+    fun observeTasks(): LiveData<Result<List<Task>>>
+
+    suspend fun getTasks(): Result<List<Task>>
+
+    suspend fun refreshTasks()
+
+    fun observeTask(taskId: String): LiveData<Result<Task>>
+
+    suspend fun getTask(taskId: String): Result<Task>
+
+    suspend fun refreshTask(taskId: String)
+
+    suspend fun saveTask(task: Task)
+
+    suspend fun completeTask(task: Task)
+
+    suspend fun completeTask(taskId: String)
+
+    suspend fun activateTask(task: Task)
+
+    suspend fun activateTask(taskId: String)
+
+    suspend fun clearCompletedTasks()
+
+    suspend fun deleteAllTasks()
+
+    suspend fun deleteTask(taskId: String)
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/source/TasksRepository.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/source/TasksRepository.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.architecture.blueprints.todoapp.data.source
+
+import androidx.lifecycle.LiveData
+import com.example.android.architecture.blueprints.todoapp.data.Result
+import com.example.android.architecture.blueprints.todoapp.data.Task
+
+/**
+ * Interface to the data layer.
+ */
+interface TasksRepository {
+
+    fun observeTasks(): LiveData<Result<List<Task>>>
+
+    suspend fun getTasks(forceUpdate: Boolean = false): Result<List<Task>>
+
+    suspend fun refreshTasks()
+
+    fun observeTask(taskId: String): LiveData<Result<Task>>
+
+    suspend fun getTask(taskId: String, forceUpdate: Boolean = false): Result<Task>
+
+    suspend fun refreshTask(taskId: String)
+
+    suspend fun saveTask(task: Task)
+
+    suspend fun completeTask(task: Task)
+
+    suspend fun completeTask(taskId: String)
+
+    suspend fun activateTask(task: Task)
+
+    suspend fun activateTask(taskId: String)
+
+    suspend fun clearCompletedTasks()
+
+    suspend fun deleteAllTasks()
+
+    suspend fun deleteTask(taskId: String)
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/source/local/TasksDao.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/source/local/TasksDao.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.architecture.blueprints.todoapp.data.source.local
+
+import androidx.lifecycle.LiveData
+import androidx.room.Dao
+import androidx.room.Insert
+import androidx.room.OnConflictStrategy
+import androidx.room.Query
+import androidx.room.Update
+import com.example.android.architecture.blueprints.todoapp.data.Task
+
+/**
+ * Data Access Object for the tasks table.
+ */
+@Dao
+interface TasksDao {
+
+    /**
+     * Observes list of tasks.
+     *
+     * @return all tasks.
+     */
+    @Query("SELECT * FROM Tasks")
+    fun observeTasks(): LiveData<List<Task>>
+
+    /**
+     * Observes a single task.
+     *
+     * @param taskId the task id.
+     * @return the task with taskId.
+     */
+    @Query("SELECT * FROM Tasks WHERE entryid = :taskId")
+    fun observeTaskById(taskId: String): LiveData<Task>
+
+    /**
+     * Select all tasks from the tasks table.
+     *
+     * @return all tasks.
+     */
+    @Query("SELECT * FROM Tasks")
+    suspend fun getTasks(): List<Task>
+
+    /**
+     * Select a task by id.
+     *
+     * @param taskId the task id.
+     * @return the task with taskId.
+     */
+    @Query("SELECT * FROM Tasks WHERE entryid = :taskId")
+    suspend fun getTaskById(taskId: String): Task?
+
+    /**
+     * Insert a task in the database. If the task already exists, replace it.
+     *
+     * @param task the task to be inserted.
+     */
+    @Insert(onConflict = OnConflictStrategy.REPLACE)
+    suspend fun insertTask(task: Task)
+
+    /**
+     * Update a task.
+     *
+     * @param task task to be updated
+     * @return the number of tasks updated. This should always be 1.
+     */
+    @Update
+    suspend fun updateTask(task: Task): Int
+
+    /**
+     * Update the complete status of a task
+     *
+     * @param taskId id of the task
+     * @param completed status to be updated
+     */
+    @Query("UPDATE tasks SET completed = :completed WHERE entryid = :taskId")
+    suspend fun updateCompleted(taskId: String, completed: Boolean)
+
+    /**
+     * Delete a task by id.
+     *
+     * @return the number of tasks deleted. This should always be 1.
+     */
+    @Query("DELETE FROM Tasks WHERE entryid = :taskId")
+    suspend fun deleteTaskById(taskId: String): Int
+
+    /**
+     * Delete all tasks.
+     */
+    @Query("DELETE FROM Tasks")
+    suspend fun deleteTasks()
+
+    /**
+     * Delete all completed tasks from the table.
+     *
+     * @return the number of tasks deleted.
+     */
+    @Query("DELETE FROM Tasks WHERE completed = 1")
+    suspend fun deleteCompletedTasks(): Int
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/source/local/TasksLocalDataSource.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/source/local/TasksLocalDataSource.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.data.source.local
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.map
+import com.example.android.architecture.blueprints.todoapp.data.Result
+import com.example.android.architecture.blueprints.todoapp.data.Result.Error
+import com.example.android.architecture.blueprints.todoapp.data.Result.Success
+import com.example.android.architecture.blueprints.todoapp.data.Task
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksDataSource
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.withContext
+
+/**
+ * Concrete implementation of a data source as a db.
+ */
+class TasksLocalDataSource internal constructor(
+    private val tasksDao: TasksDao,
+    private val ioDispatcher: CoroutineDispatcher = Dispatchers.IO
+) : TasksDataSource {
+
+    override fun observeTasks(): LiveData<Result<List<Task>>> {
+        return tasksDao.observeTasks().map {
+            Success(it)
+        }
+    }
+
+    override fun observeTask(taskId: String): LiveData<Result<Task>> {
+        return tasksDao.observeTaskById(taskId).map {
+            Success(it)
+        }
+    }
+
+    override suspend fun refreshTask(taskId: String) {
+        // NO-OP
+    }
+
+    override suspend fun refreshTasks() {
+        // NO-OP
+    }
+
+    override suspend fun getTasks(): Result<List<Task>> = withContext(ioDispatcher) {
+        return@withContext try {
+            Success(tasksDao.getTasks())
+        } catch (e: Exception) {
+            Error(e)
+        }
+    }
+
+    override suspend fun getTask(taskId: String): Result<Task> = withContext(ioDispatcher) {
+        try {
+            val task = tasksDao.getTaskById(taskId)
+            if (task != null) {
+                return@withContext Success(task)
+            } else {
+                return@withContext Error(Exception("Task not found!"))
+            }
+        } catch (e: Exception) {
+            return@withContext Error(e)
+        }
+    }
+
+    override suspend fun saveTask(task: Task) = withContext(ioDispatcher) {
+        tasksDao.insertTask(task)
+    }
+
+    override suspend fun completeTask(task: Task) = withContext(ioDispatcher) {
+        tasksDao.updateCompleted(task.id, true)
+    }
+
+    override suspend fun completeTask(taskId: String) {
+        tasksDao.updateCompleted(taskId, true)
+    }
+
+    override suspend fun activateTask(task: Task) = withContext(ioDispatcher) {
+        tasksDao.updateCompleted(task.id, false)
+    }
+
+    override suspend fun activateTask(taskId: String) {
+        tasksDao.updateCompleted(taskId, false)
+    }
+
+    override suspend fun clearCompletedTasks() = withContext<Unit>(ioDispatcher) {
+        tasksDao.deleteCompletedTasks()
+    }
+
+    override suspend fun deleteAllTasks() = withContext(ioDispatcher) {
+        tasksDao.deleteTasks()
+    }
+
+    override suspend fun deleteTask(taskId: String) = withContext<Unit>(ioDispatcher) {
+        tasksDao.deleteTaskById(taskId)
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/source/local/ToDoDatabase.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/data/source/local/ToDoDatabase.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.architecture.blueprints.todoapp.data.source.local
+
+import androidx.room.Database
+import androidx.room.RoomDatabase
+import com.example.android.architecture.blueprints.todoapp.data.Task
+
+/**
+ * The Room Database that contains the Task table.
+ *
+ * Note that exportSchema should be true in production databases.
+ */
+@Database(entities = [Task::class], version = 1, exportSchema = false)
+abstract class ToDoDatabase : RoomDatabase() {
+
+    abstract fun taskDao(): TasksDao
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/statistics/StatisticsFragment.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/statistics/StatisticsFragment.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.statistics
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.databinding.DataBindingUtil
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.viewModels
+import com.example.android.architecture.blueprints.todoapp.R
+import com.example.android.architecture.blueprints.todoapp.databinding.StatisticsFragBinding
+import com.example.android.architecture.blueprints.todoapp.util.getViewModelFactory
+import com.example.android.architecture.blueprints.todoapp.util.setupRefreshLayout
+
+/**
+ * Main UI for the statistics screen.
+ */
+class StatisticsFragment : Fragment() {
+
+    private lateinit var viewDataBinding: StatisticsFragBinding
+
+    private val viewModel by viewModels<StatisticsViewModel> { getViewModelFactory() }
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        viewDataBinding = DataBindingUtil.inflate(
+            inflater, R.layout.statistics_frag, container,
+            false
+        )
+        return viewDataBinding.root
+    }
+
+    override fun onActivityCreated(savedInstanceState: Bundle?) {
+        super.onActivityCreated(savedInstanceState)
+        viewDataBinding.viewmodel = viewModel
+        viewDataBinding.lifecycleOwner = this.viewLifecycleOwner
+        this.setupRefreshLayout(viewDataBinding.refreshLayout)
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/statistics/StatisticsUtils.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/statistics/StatisticsUtils.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.architecture.blueprints.todoapp.statistics
+
+import com.example.android.architecture.blueprints.todoapp.data.Task
+
+/**
+ * Function that does some trivial computation. Used to showcase unit tests.
+ */
+internal fun getActiveAndCompletedStats(tasks: List<Task>?): StatsResult {
+
+    return if (tasks == null || tasks.isEmpty()) {
+        StatsResult(0f, 0f)
+    } else {
+        val totalTasks = tasks.size
+        val numberOfActiveTasks = tasks.count { it.isActive }
+        StatsResult(
+            activeTasksPercent = 100f * numberOfActiveTasks / tasks.size,
+            completedTasksPercent = 100f * (totalTasks - numberOfActiveTasks) / tasks.size
+        )
+    }
+}
+
+data class StatsResult(val activeTasksPercent: Float, val completedTasksPercent: Float)
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/statistics/StatisticsViewModel.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/statistics/StatisticsViewModel.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.architecture.blueprints.todoapp.statistics
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.map
+import androidx.lifecycle.viewModelScope
+import com.example.android.architecture.blueprints.todoapp.data.Result
+import com.example.android.architecture.blueprints.todoapp.data.Result.Error
+import com.example.android.architecture.blueprints.todoapp.data.Result.Success
+import com.example.android.architecture.blueprints.todoapp.data.Task
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksRepository
+import kotlinx.coroutines.launch
+
+/**
+ * ViewModel for the statistics screen.
+ */
+class StatisticsViewModel(
+    private val tasksRepository: TasksRepository
+) : ViewModel() {
+
+    private val tasks: LiveData<Result<List<Task>>> = tasksRepository.observeTasks()
+    private val _dataLoading = MutableLiveData<Boolean>(false)
+    private val stats: LiveData<StatsResult?> = tasks.map {
+        if (it is Success) {
+            getActiveAndCompletedStats(it.data)
+        } else {
+            null
+        }
+    }
+
+    val activeTasksPercent = stats.map {
+        it?.activeTasksPercent ?: 0f }
+    val completedTasksPercent: LiveData<Float> = stats.map { it?.completedTasksPercent ?: 0f }
+    val dataLoading: LiveData<Boolean> = _dataLoading
+    val error: LiveData<Boolean> = tasks.map { it is Error }
+    val empty: LiveData<Boolean> = tasks.map { (it as? Success)?.data.isNullOrEmpty() }
+
+    fun refresh() {
+        _dataLoading.value = true
+        viewModelScope.launch {
+            tasksRepository.refreshTasks()
+            _dataLoading.value = false
+        }
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/taskdetail/TaskDetailFragment.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/taskdetail/TaskDetailFragment.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.taskdetail
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.Menu
+import android.view.MenuInflater
+import android.view.MenuItem
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.viewModels
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.fragment.navArgs
+import com.example.android.architecture.blueprints.todoapp.EventObserver
+import com.example.android.architecture.blueprints.todoapp.R
+import com.example.android.architecture.blueprints.todoapp.databinding.TaskdetailFragBinding
+import com.example.android.architecture.blueprints.todoapp.tasks.DELETE_RESULT_OK
+import com.example.android.architecture.blueprints.todoapp.util.getViewModelFactory
+import com.example.android.architecture.blueprints.todoapp.util.setupRefreshLayout
+import com.example.android.architecture.blueprints.todoapp.util.setupSnackbar
+import com.google.android.material.snackbar.Snackbar
+
+/**
+ * Main UI for the task detail screen.
+ */
+class TaskDetailFragment : Fragment() {
+    private lateinit var viewDataBinding: TaskdetailFragBinding
+
+    private val args: TaskDetailFragmentArgs by navArgs()
+
+    private val viewModel by viewModels<TaskDetailViewModel> { getViewModelFactory() }
+
+    override fun onActivityCreated(savedInstanceState: Bundle?) {
+        super.onActivityCreated(savedInstanceState)
+        setupFab()
+        view?.setupSnackbar(this, viewModel.snackbarText, Snackbar.LENGTH_SHORT)
+        setupNavigation()
+        this.setupRefreshLayout(viewDataBinding.refreshLayout)
+    }
+
+    private fun setupNavigation() {
+        viewModel.deleteTaskEvent.observe(this, EventObserver {
+            val action = TaskDetailFragmentDirections
+                .actionTaskDetailFragmentToTasksFragment(DELETE_RESULT_OK)
+            findNavController().navigate(action)
+        })
+        viewModel.editTaskEvent.observe(this, EventObserver {
+            val action = TaskDetailFragmentDirections
+                .actionTaskDetailFragmentToAddEditTaskFragment(
+                    args.taskId,
+                    resources.getString(R.string.edit_task)
+                )
+            findNavController().navigate(action)
+        })
+    }
+
+    private fun setupFab() {
+        activity?.findViewById<View>(R.id.edit_task_fab)?.setOnClickListener {
+            viewModel.editTask()
+        }
+    }
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        val view = inflater.inflate(R.layout.taskdetail_frag, container, false)
+        viewDataBinding = TaskdetailFragBinding.bind(view).apply {
+            viewmodel = viewModel
+        }
+        viewDataBinding.lifecycleOwner = this.viewLifecycleOwner
+
+        viewModel.start(args.taskId)
+
+        setHasOptionsMenu(true)
+        return view
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+        return when (item.itemId) {
+            R.id.menu_delete -> {
+                viewModel.deleteTask()
+                true
+            }
+            else -> false
+        }
+    }
+
+    override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
+        inflater.inflate(R.menu.taskdetail_fragment_menu, menu)
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/taskdetail/TaskDetailViewModel.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/taskdetail/TaskDetailViewModel.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.taskdetail
+
+import androidx.annotation.StringRes
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.map
+import androidx.lifecycle.switchMap
+import androidx.lifecycle.viewModelScope
+import com.example.android.architecture.blueprints.todoapp.Event
+import com.example.android.architecture.blueprints.todoapp.R
+import com.example.android.architecture.blueprints.todoapp.data.Result
+import com.example.android.architecture.blueprints.todoapp.data.Result.Success
+import com.example.android.architecture.blueprints.todoapp.data.Task
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksRepository
+import kotlinx.coroutines.launch
+
+/**
+ * ViewModel for the Details screen.
+ */
+class TaskDetailViewModel(
+    private val tasksRepository: TasksRepository
+) : ViewModel() {
+
+    private val _taskId = MutableLiveData<String>()
+
+    private val _task = _taskId.switchMap { taskId ->
+        tasksRepository.observeTask(taskId).map { computeResult(it) }
+    }
+    val task: LiveData<Task?> = _task
+
+    val isDataAvailable: LiveData<Boolean> = _task.map { it != null }
+
+    private val _dataLoading = MutableLiveData<Boolean>()
+    val dataLoading: LiveData<Boolean> = _dataLoading
+
+    private val _editTaskEvent = MutableLiveData<Event<Unit>>()
+    val editTaskEvent: LiveData<Event<Unit>> = _editTaskEvent
+
+    private val _deleteTaskEvent = MutableLiveData<Event<Unit>>()
+    val deleteTaskEvent: LiveData<Event<Unit>> = _deleteTaskEvent
+
+    private val _snackbarText = MutableLiveData<Event<Int>>()
+    val snackbarText: LiveData<Event<Int>> = _snackbarText
+
+    // This LiveData depends on another so we can use a transformation.
+    val completed: LiveData<Boolean> = _task.map { input: Task? ->
+        input?.isCompleted ?: false
+    }
+
+    fun deleteTask() = viewModelScope.launch {
+        _taskId.value?.let {
+            tasksRepository.deleteTask(it)
+            _deleteTaskEvent.value = Event(Unit)
+        }
+    }
+
+    fun editTask() {
+        _editTaskEvent.value = Event(Unit)
+    }
+
+    fun setCompleted(completed: Boolean) = viewModelScope.launch {
+        val task = _task.value ?: return@launch
+        if (completed) {
+            tasksRepository.completeTask(task)
+            showSnackbarMessage(R.string.task_marked_complete)
+        } else {
+            tasksRepository.activateTask(task)
+            showSnackbarMessage(R.string.task_marked_active)
+        }
+    }
+
+    fun start(taskId: String?) {
+        // If we're already loading or already loaded, return (might be a config change)
+        if (_dataLoading.value == true || taskId == _taskId.value) {
+            return
+        }
+        // Trigger the load
+        _taskId.value = taskId
+    }
+
+    private fun computeResult(taskResult: Result<Task>): Task? {
+        return if (taskResult is Success) {
+            taskResult.data
+        } else {
+            showSnackbarMessage(R.string.loading_tasks_error)
+            null
+        }
+    }
+
+    fun refresh() {
+        // Refresh the repository and the task will be updated automatically.
+        _task.value?.let {
+            _dataLoading.value = true
+            viewModelScope.launch {
+                tasksRepository.refreshTask(it.id)
+                _dataLoading.value = false
+            }
+        }
+    }
+
+    private fun showSnackbarMessage(@StringRes message: Int) {
+        _snackbarText.value = Event(message)
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksActivity.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksActivity.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.tasks
+
+import android.app.Activity
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+import androidx.drawerlayout.widget.DrawerLayout
+import androidx.navigation.NavController
+import androidx.navigation.findNavController
+import androidx.navigation.ui.AppBarConfiguration
+import androidx.navigation.ui.navigateUp
+import androidx.navigation.ui.setupActionBarWithNavController
+import androidx.navigation.ui.setupWithNavController
+import com.example.android.architecture.blueprints.todoapp.R
+import com.google.android.material.navigation.NavigationView
+
+/**
+ * Main activity for the todoapp. Holds the Navigation Host Fragment and the Drawer, Toolbar, etc.
+ */
+class TasksActivity : AppCompatActivity() {
+
+    private lateinit var drawerLayout: DrawerLayout
+    private lateinit var appBarConfiguration: AppBarConfiguration
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.tasks_act)
+        setupNavigationDrawer()
+        setSupportActionBar(findViewById(R.id.toolbar))
+
+        val navController: NavController = findNavController(R.id.nav_host_fragment)
+        appBarConfiguration =
+            AppBarConfiguration.Builder(R.id.tasks_fragment_dest, R.id.statistics_fragment_dest)
+                .setDrawerLayout(drawerLayout)
+                .build()
+        setupActionBarWithNavController(navController, appBarConfiguration)
+        findViewById<NavigationView>(R.id.nav_view)
+            .setupWithNavController(navController)
+    }
+
+    override fun onSupportNavigateUp(): Boolean {
+        return findNavController(R.id.nav_host_fragment).navigateUp(appBarConfiguration) ||
+            super.onSupportNavigateUp()
+    }
+
+    private fun setupNavigationDrawer() {
+        drawerLayout = (findViewById<DrawerLayout>(R.id.drawer_layout))
+            .apply {
+                setStatusBarBackground(R.color.colorPrimaryDark)
+            }
+    }
+}
+
+// Keys for navigation
+const val ADD_EDIT_RESULT_OK = Activity.RESULT_FIRST_USER + 1
+const val DELETE_RESULT_OK = Activity.RESULT_FIRST_USER + 2
+const val EDIT_RESULT_OK = Activity.RESULT_FIRST_USER + 3
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksAdapter.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksAdapter.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.tasks
+
+import android.view.LayoutInflater
+import android.view.ViewGroup
+import androidx.recyclerview.widget.DiffUtil
+import androidx.recyclerview.widget.ListAdapter
+import androidx.recyclerview.widget.RecyclerView
+import com.example.android.architecture.blueprints.todoapp.data.Task
+import com.example.android.architecture.blueprints.todoapp.databinding.TaskItemBinding
+import com.example.android.architecture.blueprints.todoapp.tasks.TasksAdapter.ViewHolder
+
+/**
+ * Adapter for the task list. Has a reference to the [TasksViewModel] to send actions back to it.
+ */
+class TasksAdapter(private val viewModel: TasksViewModel) :
+    ListAdapter<Task, ViewHolder>(TaskDiffCallback()) {
+
+    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
+        val item = getItem(position)
+
+        holder.bind(viewModel, item)
+    }
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
+        return ViewHolder.from(parent)
+    }
+
+    class ViewHolder private constructor(val binding: TaskItemBinding) :
+        RecyclerView.ViewHolder(binding.root) {
+
+        fun bind(viewModel: TasksViewModel, item: Task) {
+
+            binding.viewmodel = viewModel
+            binding.task = item
+            binding.executePendingBindings()
+        }
+
+        companion object {
+            fun from(parent: ViewGroup): ViewHolder {
+                val layoutInflater = LayoutInflater.from(parent.context)
+                val binding = TaskItemBinding.inflate(layoutInflater, parent, false)
+
+                return ViewHolder(binding)
+            }
+        }
+    }
+}
+
+/**
+ * Callback for calculating the diff between two non-null items in a list.
+ *
+ * Used by ListAdapter to calculate the minimum number of changes between and old list and a new
+ * list that's been passed to `submitList`.
+ */
+class TaskDiffCallback : DiffUtil.ItemCallback<Task>() {
+    override fun areItemsTheSame(oldItem: Task, newItem: Task): Boolean {
+        return oldItem.id == newItem.id
+    }
+
+    override fun areContentsTheSame(oldItem: Task, newItem: Task): Boolean {
+        return oldItem == newItem
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksFilterType.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksFilterType.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.tasks
+
+/**
+ * Used with the filter spinner in the tasks list.
+ */
+enum class TasksFilterType {
+    /**
+     * Do not filter tasks.
+     */
+    ALL_TASKS,
+
+    /**
+     * Filters only the active (not completed yet) tasks.
+     */
+    ACTIVE_TASKS,
+
+    /**
+     * Filters only the completed tasks.
+     */
+    COMPLETED_TASKS
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksFragment.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksFragment.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.architecture.blueprints.todoapp.tasks
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.Menu
+import android.view.MenuInflater
+import android.view.MenuItem
+import android.view.View
+import android.view.ViewGroup
+import androidx.appcompat.widget.PopupMenu
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.viewModels
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.fragment.navArgs
+import com.example.android.architecture.blueprints.todoapp.EventObserver
+import com.example.android.architecture.blueprints.todoapp.R
+import com.example.android.architecture.blueprints.todoapp.data.Task
+import com.example.android.architecture.blueprints.todoapp.databinding.TasksFragBinding
+import com.example.android.architecture.blueprints.todoapp.util.getViewModelFactory
+import com.example.android.architecture.blueprints.todoapp.util.setupRefreshLayout
+import com.example.android.architecture.blueprints.todoapp.util.setupSnackbar
+import com.google.android.material.floatingactionbutton.FloatingActionButton
+import com.google.android.material.snackbar.Snackbar
+import timber.log.Timber
+
+/**
+ * Display a grid of [Task]s. User can choose to view all, active or completed tasks.
+ */
+class TasksFragment : Fragment() {
+
+    private val viewModel by viewModels<TasksViewModel> { getViewModelFactory() }
+
+    private val args: TasksFragmentArgs by navArgs()
+
+    private lateinit var viewDataBinding: TasksFragBinding
+
+    private lateinit var listAdapter: TasksAdapter
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        viewDataBinding = TasksFragBinding.inflate(inflater, container, false).apply {
+            viewmodel = viewModel
+        }
+        setHasOptionsMenu(true)
+        return viewDataBinding.root
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem) =
+        when (item.itemId) {
+            R.id.menu_clear -> {
+                viewModel.clearCompletedTasks()
+                true
+            }
+            R.id.menu_filter -> {
+                showFilteringPopUpMenu()
+                true
+            }
+            R.id.menu_refresh -> {
+                viewModel.loadTasks(true)
+                true
+            }
+            else -> false
+        }
+
+    override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
+        inflater.inflate(R.menu.tasks_fragment_menu, menu)
+    }
+
+    override fun onActivityCreated(savedInstanceState: Bundle?) {
+        super.onActivityCreated(savedInstanceState)
+
+        // Set the lifecycle owner to the lifecycle of the view
+        viewDataBinding.lifecycleOwner = this.viewLifecycleOwner
+        setupSnackbar()
+        setupListAdapter()
+        setupRefreshLayout(viewDataBinding.refreshLayout, viewDataBinding.tasksList)
+        setupNavigation()
+        setupFab()
+    }
+
+    private fun setupNavigation() {
+        viewModel.openTaskEvent.observe(this, EventObserver {
+            openTaskDetails(it)
+        })
+        viewModel.newTaskEvent.observe(this, EventObserver {
+            navigateToAddNewTask()
+        })
+    }
+
+    private fun setupSnackbar() {
+        view?.setupSnackbar(this, viewModel.snackbarText, Snackbar.LENGTH_SHORT)
+        arguments?.let {
+            viewModel.showEditResultMessage(args.userMessage)
+        }
+    }
+
+    private fun showFilteringPopUpMenu() {
+        val view = activity?.findViewById<View>(R.id.menu_filter) ?: return
+        PopupMenu(requireContext(), view).run {
+            menuInflater.inflate(R.menu.filter_tasks, menu)
+
+            setOnMenuItemClickListener {
+                viewModel.setFiltering(
+                    when (it.itemId) {
+                        R.id.active -> TasksFilterType.ACTIVE_TASKS
+                        R.id.completed -> TasksFilterType.COMPLETED_TASKS
+                        else -> TasksFilterType.ALL_TASKS
+                    }
+                )
+                true
+            }
+            show()
+        }
+    }
+
+    private fun setupFab() {
+        activity?.findViewById<FloatingActionButton>(R.id.add_task_fab)?.let {
+            it.setOnClickListener {
+                navigateToAddNewTask()
+            }
+        }
+    }
+
+    private fun navigateToAddNewTask() {
+        val action = TasksFragmentDirections
+            .actionTasksFragmentToAddEditTaskFragment(
+                null,
+                resources.getString(R.string.add_task)
+            )
+        findNavController().navigate(action)
+    }
+
+    private fun openTaskDetails(taskId: String) {
+        val action = TasksFragmentDirections.actionTasksFragmentToTaskDetailFragment(taskId)
+        findNavController().navigate(action)
+    }
+
+    private fun setupListAdapter() {
+        val viewModel = viewDataBinding.viewmodel
+        if (viewModel != null) {
+            listAdapter = TasksAdapter(viewModel)
+            viewDataBinding.tasksList.adapter = listAdapter
+        } else {
+            Timber.w("ViewModel not initialized when attempting to set up adapter.")
+        }
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksListBindings.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksListBindings.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.tasks
+
+import android.graphics.Paint
+import android.widget.TextView
+import androidx.databinding.BindingAdapter
+import androidx.recyclerview.widget.RecyclerView
+import com.example.android.architecture.blueprints.todoapp.data.Task
+
+/**
+ * [BindingAdapter]s for the [Task]s list.
+ */
+@BindingAdapter("app:items")
+fun setItems(listView: RecyclerView, items: List<Task>?) {
+    items?.let {
+        (listView.adapter as TasksAdapter).submitList(items)
+    }
+}
+
+@BindingAdapter("app:completedTask")
+fun setStyle(textView: TextView, enabled: Boolean) {
+    if (enabled) {
+        textView.paintFlags = textView.paintFlags or Paint.STRIKE_THRU_TEXT_FLAG
+    } else {
+        textView.paintFlags = textView.paintFlags and Paint.STRIKE_THRU_TEXT_FLAG.inv()
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksViewModel.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksViewModel.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.tasks
+
+import androidx.annotation.DrawableRes
+import androidx.annotation.StringRes
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.SavedStateHandle
+import androidx.lifecycle.Transformations
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.distinctUntilChanged
+import androidx.lifecycle.switchMap
+import androidx.lifecycle.viewModelScope
+import com.example.android.architecture.blueprints.todoapp.Event
+import com.example.android.architecture.blueprints.todoapp.R
+import com.example.android.architecture.blueprints.todoapp.data.Result
+import com.example.android.architecture.blueprints.todoapp.data.Result.Success
+import com.example.android.architecture.blueprints.todoapp.data.Task
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksDataSource
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksRepository
+import com.example.android.architecture.blueprints.todoapp.tasks.TasksFilterType.ACTIVE_TASKS
+import com.example.android.architecture.blueprints.todoapp.tasks.TasksFilterType.ALL_TASKS
+import com.example.android.architecture.blueprints.todoapp.tasks.TasksFilterType.COMPLETED_TASKS
+import kotlinx.coroutines.launch
+
+/**
+ * ViewModel for the task list screen.
+ */
+class TasksViewModel(
+    private val tasksRepository: TasksRepository,
+    private val savedStateHandle: SavedStateHandle
+) : ViewModel() {
+
+    private val _forceUpdate = MutableLiveData<Boolean>(false)
+
+    private val _items: LiveData<List<Task>> = _forceUpdate.switchMap { forceUpdate ->
+        if (forceUpdate) {
+            _dataLoading.value = true
+            viewModelScope.launch {
+                tasksRepository.refreshTasks()
+                _dataLoading.value = false
+            }
+        }
+        tasksRepository.observeTasks().distinctUntilChanged().switchMap { filterTasks(it) }
+    }
+
+    val items: LiveData<List<Task>> = _items
+
+    private val _dataLoading = MutableLiveData<Boolean>()
+    val dataLoading: LiveData<Boolean> = _dataLoading
+
+    private val _currentFilteringLabel = MutableLiveData<Int>()
+    val currentFilteringLabel: LiveData<Int> = _currentFilteringLabel
+
+    private val _noTasksLabel = MutableLiveData<Int>()
+    val noTasksLabel: LiveData<Int> = _noTasksLabel
+
+    private val _noTaskIconRes = MutableLiveData<Int>()
+    val noTaskIconRes: LiveData<Int> = _noTaskIconRes
+
+    private val _tasksAddViewVisible = MutableLiveData<Boolean>()
+    val tasksAddViewVisible: LiveData<Boolean> = _tasksAddViewVisible
+
+    private val _snackbarText = MutableLiveData<Event<Int>>()
+    val snackbarText: LiveData<Event<Int>> = _snackbarText
+
+    // Not used at the moment
+    private val isDataLoadingError = MutableLiveData<Boolean>()
+
+    private val _openTaskEvent = MutableLiveData<Event<String>>()
+    val openTaskEvent: LiveData<Event<String>> = _openTaskEvent
+
+    private val _newTaskEvent = MutableLiveData<Event<Unit>>()
+    val newTaskEvent: LiveData<Event<Unit>> = _newTaskEvent
+
+    private var resultMessageShown: Boolean = false
+
+    // This LiveData depends on another so we can use a transformation.
+    val empty: LiveData<Boolean> = Transformations.map(_items) {
+        it.isEmpty()
+    }
+
+    init {
+        // Set initial state
+        setFiltering(getSavedFilterType())
+        loadTasks(true)
+    }
+
+    /**
+     * Sets the current task filtering type.
+     *
+     * @param requestType Can be [TasksFilterType.ALL_TASKS],
+     * [TasksFilterType.COMPLETED_TASKS], or
+     * [TasksFilterType.ACTIVE_TASKS]
+     */
+    fun setFiltering(requestType: TasksFilterType) {
+        savedStateHandle.set(TASKS_FILTER_SAVED_STATE_KEY, requestType)
+
+        // Depending on the filter type, set the filtering label, icon drawables, etc.
+        when (requestType) {
+            ALL_TASKS -> {
+                setFilter(
+                    R.string.label_all, R.string.no_tasks_all,
+                    R.drawable.logo_no_fill, true
+                )
+            }
+            ACTIVE_TASKS -> {
+                setFilter(
+                    R.string.label_active, R.string.no_tasks_active,
+                    R.drawable.ic_check_circle_96dp, false
+                )
+            }
+            COMPLETED_TASKS -> {
+                setFilter(
+                    R.string.label_completed, R.string.no_tasks_completed,
+                    R.drawable.ic_verified_user_96dp, false
+                )
+            }
+        }
+        // Refresh list
+        loadTasks(false)
+    }
+
+    private fun setFilter(
+        @StringRes filteringLabelString: Int,
+        @StringRes noTasksLabelString: Int,
+        @DrawableRes noTaskIconDrawable: Int,
+        tasksAddVisible: Boolean
+    ) {
+        _currentFilteringLabel.value = filteringLabelString
+        _noTasksLabel.value = noTasksLabelString
+        _noTaskIconRes.value = noTaskIconDrawable
+        _tasksAddViewVisible.value = tasksAddVisible
+    }
+
+    fun clearCompletedTasks() {
+        viewModelScope.launch {
+            tasksRepository.clearCompletedTasks()
+            showSnackbarMessage(R.string.completed_tasks_cleared)
+        }
+    }
+
+    fun completeTask(task: Task, completed: Boolean) = viewModelScope.launch {
+        if (completed) {
+            tasksRepository.completeTask(task)
+            showSnackbarMessage(R.string.task_marked_complete)
+        } else {
+            tasksRepository.activateTask(task)
+            showSnackbarMessage(R.string.task_marked_active)
+        }
+    }
+
+    /**
+     * Called by the Data Binding library and the FAB's click listener.
+     */
+    fun addNewTask() {
+        _newTaskEvent.value = Event(Unit)
+    }
+
+    /**
+     * Called by Data Binding.
+     */
+    fun openTask(taskId: String) {
+        _openTaskEvent.value = Event(taskId)
+    }
+
+    fun showEditResultMessage(result: Int) {
+        if (resultMessageShown) return
+        when (result) {
+            EDIT_RESULT_OK -> showSnackbarMessage(R.string.successfully_saved_task_message)
+            ADD_EDIT_RESULT_OK -> showSnackbarMessage(R.string.successfully_added_task_message)
+            DELETE_RESULT_OK -> showSnackbarMessage(R.string.successfully_deleted_task_message)
+        }
+        resultMessageShown = true
+    }
+
+    private fun showSnackbarMessage(message: Int) {
+        _snackbarText.value = Event(message)
+    }
+
+    private fun filterTasks(tasksResult: Result<List<Task>>): LiveData<List<Task>> {
+        // TODO: This is a good case for liveData builder. Replace when stable.
+        val result = MutableLiveData<List<Task>>()
+
+        if (tasksResult is Success) {
+            isDataLoadingError.value = false
+            viewModelScope.launch {
+                result.value = filterItems(tasksResult.data, getSavedFilterType())
+            }
+        } else {
+            result.value = emptyList()
+            showSnackbarMessage(R.string.loading_tasks_error)
+            isDataLoadingError.value = true
+        }
+
+        return result
+    }
+
+    /**
+     * @param forceUpdate Pass in true to refresh the data in the [TasksDataSource]
+     */
+    fun loadTasks(forceUpdate: Boolean) {
+        _forceUpdate.value = forceUpdate
+    }
+
+    private fun filterItems(tasks: List<Task>, filteringType: TasksFilterType): List<Task> {
+        val tasksToShow = ArrayList<Task>()
+        // We filter the tasks based on the requestType
+        for (task in tasks) {
+            when (filteringType) {
+                ALL_TASKS -> tasksToShow.add(task)
+                ACTIVE_TASKS -> if (task.isActive) {
+                    tasksToShow.add(task)
+                }
+                COMPLETED_TASKS -> if (task.isCompleted) {
+                    tasksToShow.add(task)
+                }
+            }
+        }
+        return tasksToShow
+        }
+
+    fun refresh() {
+        _forceUpdate.value = true
+    }
+
+    private fun getSavedFilterType() : TasksFilterType {
+        return savedStateHandle.get(TASKS_FILTER_SAVED_STATE_KEY) ?: ALL_TASKS
+    }
+}
+
+// Used to save the current filtering in SavedStateHandle.
+const val TASKS_FILTER_SAVED_STATE_KEY = "TASKS_FILTER_SAVED_STATE_KEY"
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/util/EspressoIdlingResource.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/util/EspressoIdlingResource.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.util
+
+import androidx.test.espresso.IdlingResource
+
+/**
+ * Contains a static reference to [IdlingResource], only available in the 'mock' build type.
+ */
+object EspressoIdlingResource {
+
+    private const val RESOURCE = "GLOBAL"
+
+    @JvmField
+    val countingIdlingResource = SimpleCountingIdlingResource(RESOURCE)
+
+    fun increment() {
+        countingIdlingResource.increment()
+    }
+
+    fun decrement() {
+        if (!countingIdlingResource.isIdleNow) {
+            countingIdlingResource.decrement()
+        }
+    }
+}
+
+inline fun <T> wrapEspressoIdlingResource(function: () -> T): T {
+    // Espresso does not work well with coroutines yet. See
+    // https://github.com/Kotlin/kotlinx.coroutines/issues/982
+    EspressoIdlingResource.increment() // Set app as busy.
+    return try {
+        function()
+    } finally {
+        EspressoIdlingResource.decrement() // Set app as idle.
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/util/FragmentExt.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/util/FragmentExt.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.util
+
+/**
+ * Extension functions for Fragment.
+ */
+
+import androidx.fragment.app.Fragment
+import com.example.android.architecture.blueprints.todoapp.TodoApplication
+import com.example.android.architecture.blueprints.todoapp.ViewModelFactory
+
+fun Fragment.getViewModelFactory(): ViewModelFactory {
+    val repository = (requireContext().applicationContext as TodoApplication).taskRepository
+    return ViewModelFactory(repository, this)
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/util/SimpleCountingIdlingResource.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/util/SimpleCountingIdlingResource.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.util
+
+import androidx.test.espresso.IdlingResource
+
+import java.util.concurrent.atomic.AtomicInteger
+
+/**
+ * An simple counter implementation of [IdlingResource] that determines idleness by
+ * maintaining an internal counter. When the counter is 0 - it is considered to be idle, when it is
+ * non-zero it is not idle. This is very similar to the way a [java.util.concurrent.Semaphore]
+ * behaves.
+ *
+ *
+ * This class can then be used to wrap up operations that while in progress should block tests from
+ * accessing the UI.
+ */
+class SimpleCountingIdlingResource(private val resourceName: String) : IdlingResource {
+
+    private val counter = AtomicInteger(0)
+
+    // written from main thread, read from any thread.
+    @Volatile
+    private var resourceCallback: IdlingResource.ResourceCallback? = null
+
+    override fun getName() = resourceName
+
+    override fun isIdleNow() = counter.get() == 0
+
+    override fun registerIdleTransitionCallback(resourceCallback: IdlingResource.ResourceCallback) {
+        this.resourceCallback = resourceCallback
+    }
+
+    /**
+     * Increments the count of in-flight transactions to the resource being monitored.
+     */
+    fun increment() {
+        counter.getAndIncrement()
+    }
+
+    /**
+     * Decrements the count of in-flight transactions to the resource being monitored.
+     * If this operation results in the counter falling below 0 - an exception is raised.
+     *
+     * @throws IllegalStateException if the counter is below 0.
+     */
+    fun decrement() {
+        val counterVal = counter.decrementAndGet()
+        if (counterVal == 0) {
+            // we've gone from non-zero to zero. That means we're idle now! Tell espresso.
+            resourceCallback?.onTransitionToIdle()
+        } else if (counterVal < 0) {
+            throw IllegalStateException("Counter has been corrupted!")
+        }
+    }
+}
--- a/app/src/main/java/com/example/android/architecture/blueprints/todoapp/util/ViewExt.kt
+++ b/app/src/main/java/com/example/android/architecture/blueprints/todoapp/util/ViewExt.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.util
+
+/**
+ * Extension functions and Binding Adapters.
+ */
+
+import android.view.View
+import androidx.core.content.ContextCompat
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.LifecycleOwner
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.Observer
+import com.example.android.architecture.blueprints.todoapp.Event
+import com.example.android.architecture.blueprints.todoapp.R
+import com.example.android.architecture.blueprints.todoapp.ScrollChildSwipeRefreshLayout
+import com.google.android.material.snackbar.Snackbar
+
+/**
+ * Transforms static java function Snackbar.make() to an extension function on View.
+ */
+fun View.showSnackbar(snackbarText: String, timeLength: Int) {
+    Snackbar.make(this, snackbarText, timeLength).run {
+        addCallback(object : Snackbar.Callback() {
+            override fun onShown(sb: Snackbar?) {
+                EspressoIdlingResource.increment()
+            }
+
+            override fun onDismissed(transientBottomBar: Snackbar?, event: Int) {
+                EspressoIdlingResource.decrement()
+            }
+        })
+        show()
+    }
+}
+
+/**
+ * Triggers a snackbar message when the value contained by snackbarTaskMessageLiveEvent is modified.
+ */
+fun View.setupSnackbar(
+    lifecycleOwner: LifecycleOwner,
+    snackbarEvent: LiveData<Event<Int>>,
+    timeLength: Int
+) {
+
+    snackbarEvent.observe(lifecycleOwner, Observer { event ->
+        event.getContentIfNotHandled()?.let {
+            showSnackbar(context.getString(it), timeLength)
+        }
+    })
+}
+
+fun Fragment.setupRefreshLayout(
+    refreshLayout: ScrollChildSwipeRefreshLayout,
+    scrollUpChild: View? = null
+) {
+    refreshLayout.setColorSchemeColors(
+        ContextCompat.getColor(requireActivity(), R.color.colorPrimary),
+        ContextCompat.getColor(requireActivity(), R.color.colorAccent),
+        ContextCompat.getColor(requireActivity(), R.color.colorPrimaryDark)
+    )
+    // Set the scrolling view in the custom SwipeRefreshLayout.
+    scrollUpChild?.let {
+        refreshLayout.scrollUpChild = it
+    }
+}
--- a/app/src/main/res/drawable/drawer_item_color.xml
+++ b/app/src/main/res/drawable/drawer_item_color.xml
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:color="@color/colorAccent" android:state_checked="true" />
+    <item android:color="@color/colorGrey" android:state_checked="false" />
+</selector>
--- a/app/src/main/res/drawable/ic_add.xml
+++ b/app/src/main/res/drawable/ic_add.xml
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24.0"
+    android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FFFFFFFF"
+        android:pathData="M19,13h-6v6h-2v-6H5v-2h6V5h2v6h6v2z" />
+</vector>
--- a/app/src/main/res/drawable/ic_assignment_turned_in_24dp.xml
+++ b/app/src/main/res/drawable/ic_assignment_turned_in_24dp.xml
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector android:alpha="0.49"
+    android:height="24dp"
+    android:viewportHeight="24.0"
+    android:viewportWidth="24.0"
+    android:width="24dp"
+    xmlns:android="http://schemas.android.com/apk/res/android">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M19,3h-4.18C14.4,1.84 13.3,1 12,1c-1.3,0 -2.4,0.84 -2.82,2H5c-1.1,0 -2,0.9 -2,2v14c0,1.1 0.9,2 2,2h14c1.1,0 2,-0.9 2,-2V5c0,-1.1 -0.9,-2 -2,-2zm-7,0c0.55,0 1,0.45 1,1s-0.45,1 -1,1 -1,-0.45 -1,-1 0.45,-1 1,-1zm-2,14l-4,-4 1.41,-1.41L10,14.17l6.59,-6.59L18,9l-8,8z" />
+</vector>
--- a/app/src/main/res/drawable/ic_check_circle_96dp.xml
+++ b/app/src/main/res/drawable/ic_check_circle_96dp.xml
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:alpha="0.49"
+    android:width="96dp"
+    android:height="96dp"
+    android:viewportHeight="24.0"
+    android:viewportWidth="24.0">
+    <path
+        android:fillColor="#2E7D32"
+        android:pathData="M12,2C6.48,2 2,6.48 2,12s4.48,10 10,10 10,-4.48 10,-10S17.52,2 12,2zm-2,15l-5,-5 1.41,-1.41L10,14.17l7.59,-7.59L19,8l-9,9z" />
+</vector>
--- a/app/src/main/res/drawable/ic_done.xml
+++ b/app/src/main/res/drawable/ic_done.xml
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportHeight="24.0"
+    android:viewportWidth="24.0">
+    <path
+        android:fillColor="#FFFFFFFF"
+        android:pathData="M9,16.17L4.83,12l-1.42,1.41L9,19 21,7l-1.41,-1.41z" />
+</vector>
--- a/app/src/main/res/drawable/ic_edit.xml
+++ b/app/src/main/res/drawable/ic_edit.xml
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24.0"
+    android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FFFFFFFF"
+        android:pathData="M3,17.25V21h3.75L17.81,9.94l-3.75,-3.75L3,17.25zM20.71,7.04c0.39,-0.39 0.39,-1.02 0,-1.41l-2.34,-2.34c-0.39,-0.39 -1.02,-0.39 -1.41,0l-1.83,1.83 3.75,3.75 1.83,-1.83z" />
+</vector>
--- a/app/src/main/res/drawable/ic_filter_list.xml
+++ b/app/src/main/res/drawable/ic_filter_list.xml
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24.0"
+    android:viewportHeight="24.0">
+    <path
+        android:fillColor="#2E7D32"
+        android:pathData="M10,18h4v-2h-4v2zM3,6v2h18V6H3zm3,7h12v-2H6v2z" />
+</vector>
--- a/app/src/main/res/drawable/ic_list.xml
+++ b/app/src/main/res/drawable/ic_list.xml
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24.0"
+    android:viewportHeight="24.0">
+    <path
+        android:fillColor="#2E7D32"
+        android:pathData="M3,13h2v-2H3v2zm0,4h2v-2H3v2zm0,-8h2V7H3v2zm4,4h14v-2H7v2zm0,4h14v-2H7v2zM7,7v2h14V7H7z" />
+</vector>
--- a/app/src/main/res/drawable/ic_menu.xml
+++ b/app/src/main/res/drawable/ic_menu.xml
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24.0"
+    android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FFFFFFFF"
+        android:pathData="M3,18h18v-2H3v2zm0,-5h18v-2H3v2zm0,-7v2h18V6H3z" />
+</vector>
--- a/app/src/main/res/drawable/ic_statistics.xml
+++ b/app/src/main/res/drawable/ic_statistics.xml
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24.0"
+    android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M19,3H5c-1.1,0 -2,0.9 -2,2v14c0,1.1 0.9,2 2,2h14c1.1,0 2,-0.9 2,-2V5c0,-1.1 -0.9,-2 -2,-2zM9,17H7v-7h2v7zm4,0h-2V7h2v10zm4,0h-2v-4h2v4z" />
+</vector>
--- a/app/src/main/res/drawable/ic_statistics_100dp.xml
+++ b/app/src/main/res/drawable/ic_statistics_100dp.xml
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector android:alpha="0.80"
+    android:height="100dp"
+    android:viewportHeight="24.0"
+    android:viewportWidth="24.0"
+    android:width="100dp"
+    xmlns:android="http://schemas.android.com/apk/res/android">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M19,3H5c-1.1,0 -2,0.9 -2,2v14c0,1.1 0.9,2 2,2h14c1.1,0 2,-0.9 2,-2V5c0,-1.1 -0.9,-2 -2,-2zM9,17H7v-7h2v7zm4,0h-2V7h2v10zm4,0h-2v-4h2v4z" />
+</vector>
--- a/app/src/main/res/drawable/ic_statistics_24dp.xml
+++ b/app/src/main/res/drawable/ic_statistics_24dp.xml
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24.0"
+    android:viewportHeight="24.0">
+    <path
+        android:fillColor="#FF000000"
+        android:pathData="M19,3H5c-1.1,0 -2,0.9 -2,2v14c0,1.1 0.9,2 2,2h14c1.1,0 2,-0.9 2,-2V5c0,-1.1 -0.9,-2 -2,-2zM9,17H7v-7h2v7zm4,0h-2V7h2v10zm4,0h-2v-4h2v4z" />
+</vector>
--- a/app/src/main/res/drawable/ic_verified_user_96dp.xml
+++ b/app/src/main/res/drawable/ic_verified_user_96dp.xml
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<vector
+    android:alpha="0.49"
+    android:height="96dp"
+    android:width="96dp"
+    android:viewportHeight="24.0"
+    android:viewportWidth="24.0"
+    xmlns:android="http://schemas.android.com/apk/res/android">
+    <path
+        android:fillColor="#2E7D32"
+        android:pathData="M12,1L3,5v6c0,5.55 3.84,10.74 9,12 5.16,-1.26 9,-6.45 9,-12V5l-9,-4zm-2,16l-4,-4 1.41,-1.41L10,14.17l6.59,-6.59L18,9l-8,8z" />
+</vector>
--- a/app/src/main/res/drawable/list_completed_touch_feedback.xml
+++ b/app/src/main/res/drawable/list_completed_touch_feedback.xml
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:state_pressed="true" android:drawable="@drawable/touchFeedback" />
+
+    <item android:drawable="@drawable/completedTaskBackground" />
+</selector>
--- a/app/src/main/res/drawable/logo_no_fill.png
+++ b/app/src/main/res/drawable/logo_no_fill.png
--- a/app/src/main/res/drawable/touch_feedback.xml
+++ b/app/src/main/res/drawable/touch_feedback.xml
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:state_pressed="true" android:drawable="@drawable/touchFeedback" />
+</selector>
--- a/app/src/main/res/drawable/trash_icon.png
+++ b/app/src/main/res/drawable/trash_icon.png
--- a/app/src/main/res/font/opensans_font.xml
+++ b/app/src/main/res/font/opensans_font.xml
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<font-family xmlns:app="http://schemas.android.com/apk/res-auto">
+    <font
+        app:fontStyle="normal"
+        app:fontWeight="400"
+        app:font="@font/opensans_regular" />
+    <font
+        app:fontStyle="normal"
+        app:fontWeight="700"
+        app:font="@font/opensans_semibold" />
+</font-family>
--- a/app/src/main/res/font/opensans_regular.ttf
+++ b/app/src/main/res/font/opensans_regular.ttf
--- a/app/src/main/res/font/opensans_semibold.ttf
+++ b/app/src/main/res/font/opensans_semibold.ttf
--- a/app/src/main/res/layout/addtask_frag.xml
+++ b/app/src/main/res/layout/addtask_frag.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <data>
+
+        <import type="android.view.View" />
+
+        <variable
+            name="viewmodel"
+            type="com.example.android.architecture.blueprints.todoapp.addedittask.AddEditTaskViewModel" />
+    </data>
+
+    <androidx.coordinatorlayout.widget.CoordinatorLayout
+        android:id="@+id/coordinator_layout"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
+
+        <com.example.android.architecture.blueprints.todoapp.ScrollChildSwipeRefreshLayout
+            android:id="@+id/refresh_layout"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            app:enabled="@{viewmodel.dataLoading}"
+            app:refreshing="@{viewmodel.dataLoading}">
+
+            <ScrollView
+                android:layout_width="match_parent"
+                android:layout_height="match_parent">
+
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:orientation="vertical"
+                    android:paddingLeft="@dimen/activity_horizontal_margin"
+                    android:paddingTop="@dimen/activity_vertical_margin"
+                    android:paddingRight="@dimen/activity_horizontal_margin"
+                    android:paddingBottom="@dimen/activity_vertical_margin"
+                    android:visibility="@{viewmodel.dataLoading ? View.GONE : View.VISIBLE}">
+
+                    <EditText
+                        android:id="@+id/add_task_title_edit_text"
+                        android:background="@null"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:hint="@string/title_hint"
+                        android:imeOptions="flagNoExtractUi"
+                        android:maxLines="1"
+                        android:text="@={viewmodel.title}"
+                        android:textStyle="bold"
+                        android:textAppearance="@style/TextAppearance.AppCompat.Title" />
+
+                    <EditText
+                        android:id="@+id/add_task_description_edit_text"
+                        android:background="@null"
+                        android:layout_width="match_parent"
+                        android:layout_height="350dp"
+                        android:gravity="top"
+                        android:hint="@string/description_hint"
+                        android:imeOptions="flagNoExtractUi"
+                        android:text="@={viewmodel.description}" />
+
+                </LinearLayout>
+            </ScrollView>
+        </com.example.android.architecture.blueprints.todoapp.ScrollChildSwipeRefreshLayout>
+
+        <com.google.android.material.floatingactionbutton.FloatingActionButton
+            android:id="@+id/save_task_fab"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_margin="@dimen/fab_margin"
+            android:src="@drawable/ic_done"
+            android:onClick="@{() -> viewmodel.saveTask()}"
+            app:fabSize="normal"
+            app:layout_anchor="@id/refresh_layout"
+            app:layout_anchorGravity="bottom|right|end" />
+    </androidx.coordinatorlayout.widget.CoordinatorLayout>
+</layout>
--- a/app/src/main/res/layout/nav_header.xml
+++ b/app/src/main/res/layout/nav_header.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<FrameLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="@dimen/header_height"
+    android:background="?attr/colorPrimaryDark"
+    android:gravity="bottom"
+    android:orientation="vertical"
+    android:padding="@dimen/header_padding"
+    android:theme="@style/ThemeOverlay.AppCompat.Dark">
+
+    <ImageView
+        android:layout_width="@dimen/header_image_width"
+        android:layout_height="wrap_content"
+        android:layout_gravity="center"
+        android:src="@drawable/logo_no_fill"
+        android:contentDescription="@string/tasks_header_image_content_description" />
+
+    <TextView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_gravity="bottom|center_horizontal"
+        android:text="@string/navigation_view_header_title"
+        android:textAppearance="@style/TextAppearance.AppCompat.Body1" />
+
+</FrameLayout>
--- a/app/src/main/res/layout/statistics_frag.xml
+++ b/app/src/main/res/layout/statistics_frag.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <data>
+
+        <import type="android.view.View" />
+
+        <variable
+            name="viewmodel"
+            type="com.example.android.architecture.blueprints.todoapp.statistics.StatisticsViewModel" />
+    </data>
+
+    <com.example.android.architecture.blueprints.todoapp.ScrollChildSwipeRefreshLayout
+        android:id="@+id/refresh_layout"
+        app:refreshing="@{viewmodel.dataLoading}"
+        app:onRefreshListener="@{viewmodel::refresh}"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
+
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:orientation="vertical"
+            android:paddingLeft="@dimen/activity_horizontal_margin"
+            android:paddingTop="@dimen/activity_vertical_margin"
+            android:paddingRight="@dimen/activity_horizontal_margin"
+            android:paddingBottom="@dimen/activity_vertical_margin">
+
+            <LinearLayout
+                android:id="@+id/statistics_layout"
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                android:orientation="vertical"
+                android:visibility="@{viewmodel.dataLoading ? View.GONE : View.VISIBLE}">
+
+                <TextView
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:text="@string/statistics_no_tasks"
+                    android:textAppearance="?android:attr/textAppearanceMedium"
+                    android:visibility="@{viewmodel.empty ? View.VISIBLE : View.GONE}" />
+
+                <TextView
+                    android:id="@+id/stats_active_text"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:paddingTop="1dp"
+                    android:text="@{@string/statistics_active_tasks(viewmodel.activeTasksPercent)}"
+                    android:textAppearance="?android:attr/textAppearanceMedium"
+                    android:visibility="@{viewmodel.empty ? View.GONE : View.VISIBLE}" />
+
+                <!-- android:paddingTop specified to temporarily work around -->
+                <!-- https://github.com/robolectric/robolectric/issues/4588 -->
+                <TextView
+                    android:id="@+id/stats_completed_text"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:paddingTop="1dp"
+                    android:text="@{@string/statistics_completed_tasks(viewmodel.completedTasksPercent)}"
+                    android:textAppearance="?android:attr/textAppearanceMedium"
+                    android:visibility="@{viewmodel.empty ? View.GONE : View.VISIBLE}" />
+
+            </LinearLayout>
+        </LinearLayout>
+
+    </com.example.android.architecture.blueprints.todoapp.ScrollChildSwipeRefreshLayout>
+</layout>
--- a/app/src/main/res/layout/task_item.xml
+++ b/app/src/main/res/layout/task_item.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <data>
+
+        <import type="android.widget.CompoundButton" />
+
+        <variable
+            name="task"
+            type="com.example.android.architecture.blueprints.todoapp.data.Task" />
+
+        <variable
+            name="viewmodel"
+            type="com.example.android.architecture.blueprints.todoapp.tasks.TasksViewModel" />
+    </data>
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="?android:attr/listPreferredItemHeight"
+        android:orientation="horizontal"
+        android:paddingLeft="@dimen/activity_horizontal_margin"
+        android:paddingRight="@dimen/activity_horizontal_margin"
+        android:paddingBottom="@dimen/list_item_padding"
+        android:paddingTop="@dimen/list_item_padding"
+        android:onClick="@{() -> viewmodel.openTask(task.id)}">
+
+        <CheckBox
+            android:id="@+id/complete_checkbox"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center_vertical"
+            android:onClick="@{(view) -> viewmodel.completeTask(task, ((CompoundButton)view).isChecked())}"
+            android:checked="@{task.completed}" />
+
+        <TextView
+            android:id="@+id/title_text"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center_vertical"
+            android:layout_marginLeft="@dimen/activity_horizontal_margin"
+            android:layout_marginStart="@dimen/activity_horizontal_margin"
+            android:textAppearance="@style/TextAppearance.AppCompat.Title"
+            android:text="@{task.titleForList}"
+            app:completedTask="@{task.completed}" />
+    </LinearLayout>
+</layout>
--- a/app/src/main/res/layout/taskdetail_frag.xml
+++ b/app/src/main/res/layout/taskdetail_frag.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <data>
+
+        <import type="android.view.View" />
+
+        <import type="android.widget.CompoundButton" />
+
+        <variable
+            name="viewmodel"
+            type="com.example.android.architecture.blueprints.todoapp.taskdetail.TaskDetailViewModel" />
+    </data>
+
+    <androidx.coordinatorlayout.widget.CoordinatorLayout
+        android:id="@+id/coordinator_layout"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
+
+
+        <com.example.android.architecture.blueprints.todoapp.ScrollChildSwipeRefreshLayout
+            android:id="@+id/refresh_layout"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            app:onRefreshListener="@{viewmodel::refresh}"
+            app:refreshing="@{viewmodel.dataLoading}">
+
+            <LinearLayout
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                android:orientation="vertical"
+                android:paddingLeft="@dimen/activity_horizontal_margin"
+                android:paddingTop="@dimen/activity_vertical_margin"
+                android:paddingRight="@dimen/activity_horizontal_margin"
+                android:paddingBottom="@dimen/activity_vertical_margin">
+
+                <LinearLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent"
+                    android:orientation="vertical"
+                    android:paddingLeft="@dimen/activity_horizontal_margin"
+                    android:paddingTop="@dimen/activity_vertical_margin"
+                    android:paddingRight="@dimen/activity_horizontal_margin"
+                    android:paddingBottom="@dimen/activity_vertical_margin"
+                    android:visibility="@{viewmodel.isDataAvailable ? View.GONE : View.VISIBLE}">
+
+                    <TextView
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:text="@string/no_data"
+                        android:textAppearance="?android:attr/textAppearanceLarge"
+                        android:visibility="@{viewmodel.dataLoading ? View.GONE : View.VISIBLE}" />
+                </LinearLayout>
+
+                <RelativeLayout
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent"
+                    android:orientation="vertical"
+                    android:paddingLeft="@dimen/activity_horizontal_margin"
+                    android:paddingTop="@dimen/activity_vertical_margin"
+                    android:paddingRight="@dimen/activity_horizontal_margin"
+                    android:paddingBottom="@dimen/activity_vertical_margin"
+                    android:visibility="@{viewmodel.isDataAvailable ? View.VISIBLE : View.GONE}">
+
+                    <!-- android:paddingTop specified to temporarily work around -->
+                    <!-- https://github.com/robolectric/robolectric/issues/4588 -->
+                    <CheckBox
+                        android:id="@+id/task_detail_complete_checkbox"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:layout_gravity="center_vertical"
+                        android:layout_marginRight="@dimen/activity_horizontal_margin"
+                        android:checked="@{viewmodel.completed}"
+                        android:onClick="@{(view) -> viewmodel.setCompleted(((CompoundButton)view).isChecked())}"
+                        android:paddingTop="1dp" />
+
+                    <TextView
+                        android:id="@+id/task_detail_title_text"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:layout_toRightOf="@id/task_detail_complete_checkbox"
+                        android:paddingTop="1dp"
+                        android:text="@{viewmodel.task.title}"
+                        android:textAppearance="?android:attr/textAppearanceLarge" />
+
+                    <TextView
+                        android:id="@+id/task_detail_description_text"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:layout_below="@id/task_detail_title_text"
+                        android:layout_toRightOf="@id/task_detail_complete_checkbox"
+                        android:paddingTop="1dp"
+                        android:text="@{viewmodel.task.description}"
+                        android:textAppearance="?android:attr/textAppearanceMedium" />
+
+                </RelativeLayout>
+            </LinearLayout>
+        </com.example.android.architecture.blueprints.todoapp.ScrollChildSwipeRefreshLayout>
+
+        <com.google.android.material.floatingactionbutton.FloatingActionButton
+            android:id="@+id/edit_task_fab"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_margin="@dimen/fab_margin"
+            android:src="@drawable/ic_edit"
+            app:fabSize="normal"
+            app:layout_anchor="@id/refresh_layout"
+            app:layout_anchorGravity="bottom|right|end" />
+
+    </androidx.coordinatorlayout.widget.CoordinatorLayout>
+</layout>
--- a/app/src/main/res/layout/tasks_act.xml
+++ b/app/src/main/res/layout/tasks_act.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<androidx.drawerlayout.widget.DrawerLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/drawer_layout"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".tasks.TasksActivity"
+    tools:openDrawer="start">
+
+    <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:orientation="vertical">
+
+        <com.google.android.material.appbar.AppBarLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content">
+
+            <androidx.appcompat.widget.Toolbar
+                android:id="@+id/toolbar"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:minHeight="?attr/actionBarSize"
+                android:theme="@style/Toolbar"
+                app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />
+        </com.google.android.material.appbar.AppBarLayout>
+
+        <fragment
+            android:id="@+id/nav_host_fragment"
+            android:name="androidx.navigation.fragment.NavHostFragment"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+
+            app:defaultNavHost="true"
+            app:navGraph="@navigation/nav_graph" />
+
+    </LinearLayout>
+
+    <!-- Navigation Drawer -->
+    <com.google.android.material.navigation.NavigationView
+        android:id="@+id/nav_view"
+        android:layout_width="wrap_content"
+        android:layout_height="match_parent"
+        android:layout_gravity="start"
+        android:fitsSystemWindows="true"
+        app:headerLayout="@layout/nav_header"
+        app:itemIconTint="@drawable/drawer_item_color"
+        app:itemTextColor="@drawable/drawer_item_color"
+        app:menu="@menu/drawer_actions" />
+
+</androidx.drawerlayout.widget.DrawerLayout>
--- a/app/src/main/res/layout/tasks_frag.xml
+++ b/app/src/main/res/layout/tasks_frag.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <data>
+
+        <import type="android.view.View" />
+
+        <import type="androidx.core.content.ContextCompat" />
+
+        <variable
+            name="viewmodel"
+            type="com.example.android.architecture.blueprints.todoapp.tasks.TasksViewModel" />
+
+    </data>
+
+
+    <androidx.coordinatorlayout.widget.CoordinatorLayout
+        android:id="@+id/coordinator_layout"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
+
+
+        <com.example.android.architecture.blueprints.todoapp.ScrollChildSwipeRefreshLayout
+            android:id="@+id/refresh_layout"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            app:onRefreshListener="@{viewmodel::refresh}"
+            app:refreshing="@{viewmodel.dataLoading}">
+
+            <RelativeLayout
+                android:id="@+id/tasks_container_layout"
+                android:layout_width="match_parent"
+                android:layout_height="match_parent"
+                android:clickable="true"
+                android:orientation="vertical">
+
+                <LinearLayout
+                    android:id="@+id/tasks_linear_layout"
+                    android:layout_width="match_parent"
+                    android:layout_height="match_parent"
+                    android:orientation="vertical"
+                    android:visibility="@{viewmodel.empty ? View.GONE : View.VISIBLE}">
+
+                    <TextView
+                        android:id="@+id/filtering_text"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:layout_marginLeft="@dimen/list_item_padding"
+                        android:layout_marginTop="@dimen/activity_vertical_margin"
+                        android:layout_marginRight="@dimen/list_item_padding"
+                        android:layout_marginBottom="@dimen/activity_vertical_margin"
+                        android:gravity="center_vertical"
+                        android:text="@{context.getString(viewmodel.currentFilteringLabel)}"
+                        android:textAppearance="@style/TextAppearance.AppCompat.Title" />
+
+                    <androidx.recyclerview.widget.RecyclerView
+                        android:id="@+id/tasks_list"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
+                        app:items="@{viewmodel.items}" />
+                </LinearLayout>
+
+                <LinearLayout
+                    android:id="@+id/no_tasks_layout"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_centerInParent="true"
+                    android:orientation="vertical"
+                    android:visibility="@{viewmodel.empty ? View.VISIBLE : View.GONE}">
+
+                    <ImageView
+                        android:id="@+id/no_tasks_icon"
+                        android:layout_width="96dp"
+                        android:layout_height="96dp"
+                        android:layout_gravity="center"
+                        android:src="@{ContextCompat.getDrawable(context, viewmodel.noTaskIconRes)}"
+                        android:contentDescription="@string/no_tasks_image_content_description" />
+
+                    <TextView
+                        android:id="@+id/no_tasks_text"
+                        android:layout_width="wrap_content"
+                        android:layout_height="wrap_content"
+                        android:layout_gravity="center"
+                        android:layout_marginBottom="@dimen/list_item_padding"
+                        android:text="@{context.getString(viewmodel.noTasksLabel)}" />
+                </LinearLayout>
+            </RelativeLayout>
+
+        </com.example.android.architecture.blueprints.todoapp.ScrollChildSwipeRefreshLayout>
+
+        <com.google.android.material.floatingactionbutton.FloatingActionButton
+            android:id="@+id/add_task_fab"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_margin="@dimen/fab_margin"
+            android:src="@drawable/ic_add"
+            app:fabSize="normal"
+            app:layout_anchor="@id/refresh_layout"
+            app:layout_anchorGravity="bottom|right|end" />
+    </androidx.coordinatorlayout.widget.CoordinatorLayout>
+</layout>
+
--- a/app/src/main/res/menu/drawer_actions.xml
+++ b/app/src/main/res/menu/drawer_actions.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<menu xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <item
+        android:id="@id/tasks_fragment_dest"
+        android:icon="@drawable/ic_list"
+        android:title="@string/list_title" />
+    <item
+        android:id="@id/statistics_fragment_dest"
+        android:icon="@drawable/ic_statistics"
+        android:title="@string/statistics_title" />
+</menu>
--- a/app/src/main/res/menu/filter_tasks.xml
+++ b/app/src/main/res/menu/filter_tasks.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<menu xmlns:android="http://schemas.android.com/apk/res/android">
+    <item
+        android:id="@+id/all"
+        android:title="@string/nav_all" />
+    <item
+        android:id="@+id/active"
+        android:title="@string/nav_active" />
+    <item
+        android:id="@+id/completed"
+        android:title="@string/nav_completed" />
+</menu>
--- a/app/src/main/res/menu/taskdetail_fragment_menu.xml
+++ b/app/src/main/res/menu/taskdetail_fragment_menu.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+    <item
+        android:id="@+id/menu_delete"
+        android:icon="@drawable/trash_icon"
+        android:title="@string/menu_delete_task"
+        app:showAsAction="always" />
+</menu>
--- a/app/src/main/res/menu/tasks_fragment_menu.xml
+++ b/app/src/main/res/menu/tasks_fragment_menu.xml
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+    <item
+        android:id="@+id/menu_filter"
+        android:title="@string/menu_filter"
+        android:icon="@drawable/ic_filter_list"
+        app:showAsAction="always" />
+    <item
+        android:id="@+id/menu_clear"
+        android:title="@string/menu_clear"
+        app:showAsAction="never" />
+    <item
+        android:id="@+id/menu_refresh"
+        android:title="@string/refresh"
+        app:showAsAction="never" />
+</menu>
--- a/app/src/main/res/mipmap-hdpi/ic_launcher.png
+++ b/app/src/main/res/mipmap-hdpi/ic_launcher.png
--- a/app/src/main/res/mipmap-mdpi/ic_launcher.png
+++ b/app/src/main/res/mipmap-mdpi/ic_launcher.png
--- a/app/src/main/res/mipmap-xhdpi/ic_launcher.png
+++ b/app/src/main/res/mipmap-xhdpi/ic_launcher.png
--- a/app/src/main/res/mipmap-xxhdpi/ic_launcher.png
+++ b/app/src/main/res/mipmap-xxhdpi/ic_launcher.png
--- a/app/src/main/res/mipmap-xxxhdpi/ic_launcher.png
+++ b/app/src/main/res/mipmap-xxxhdpi/ic_launcher.png
--- a/app/src/main/res/navigation/nav_graph.xml
+++ b/app/src/main/res/navigation/nav_graph.xml
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<navigation xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:id="@+id/nav_graph"
+    app:startDestination="@id/tasks_fragment_dest">
+
+    <fragment
+        android:id="@+id/task_detail_fragment_dest"
+        android:name="com.example.android.architecture.blueprints.todoapp.taskdetail.TaskDetailFragment"
+        android:label="Task Details">
+        <action
+            android:id="@+id/action_taskDetailFragment_to_addEditTaskFragment"
+            app:destination="@id/add_edit_task_fragment_dest" />
+        <argument
+            android:name="taskId"
+            app:argType="string" />
+        <action
+            android:id="@+id/action_taskDetailFragment_to_tasksFragment"
+            app:destination="@id/tasks_fragment_dest" />
+    </fragment>
+    <fragment
+        android:id="@+id/statistics_fragment_dest"
+        android:name="com.example.android.architecture.blueprints.todoapp.statistics.StatisticsFragment"
+        android:label="@string/app_name">
+        <action
+            android:id="@+id/action_statisticsFragment_to_tasksFragment"
+            app:destination="@id/tasks_fragment_dest"
+            />
+    </fragment>
+    <fragment
+        android:id="@+id/tasks_fragment_dest"
+        android:name="com.example.android.architecture.blueprints.todoapp.tasks.TasksFragment"
+        android:label="@string/app_name">
+        <action
+            android:id="@+id/action_tasksFragment_to_statisticsFragment"
+            app:destination="@id/statistics_fragment_dest" />
+        <action
+            android:id="@+id/action_tasksFragment_to_taskDetailFragment"
+            app:destination="@id/task_detail_fragment_dest" />
+        <action
+            android:id="@+id/action_tasksFragment_to_addEditTaskFragment"
+            app:destination="@id/add_edit_task_fragment_dest" />
+        <argument
+            android:name="userMessage"
+            app:argType="integer"
+            android:defaultValue="0" />
+    </fragment>
+    <fragment
+        android:id="@+id/add_edit_task_fragment_dest"
+        android:name="com.example.android.architecture.blueprints.todoapp.addedittask.AddEditTaskFragment"
+        android:label="{title}">
+        <argument
+            android:name="taskId"
+            app:argType="string"
+            app:nullable="true" />
+        <argument
+            android:name="title"
+            app:argType="string"
+            app:nullable="false" />
+        <action
+            android:id="@+id/action_addEditTaskFragment_to_tasksFragment"
+            app:destination="@id/tasks_fragment_dest"
+            />
+    </fragment>
+    <argument
+        android:name="userMessage"
+        android:defaultValue="0" />
+</navigation>
--- a/app/src/main/res/values-v21/styles.xml
+++ b/app/src/main/res/values-v21/styles.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<resources>
+
+    <style name="AppTheme" parent="Base.AppTheme" />
+
+    <style name="AppTheme.OverlapSystemBar" parent="Base.AppTheme">
+        <item name="android:windowDrawsSystemBarBackgrounds">false</item>
+        <item name="android:statusBarColor">@android:color/transparent</item>
+        <item name="android:windowTranslucentStatus">true</item>
+        <item name="android:fitsSystemWindows">true</item>
+    </style>
+
+</resources>
--- a/app/src/main/res/values-w820dp/dimens.xml
+++ b/app/src/main/res/values-w820dp/dimens.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<resources>
+    <!-- Example customization of dimensions originally defined in res/values/dimens.xml
+         (such as screen margins) for screens with more than 820dp of available width. This
+         would include 7" and 10" devices in landscape (~960dp and ~1280dp respectively). -->
+    <dimen name="activity_horizontal_margin">64dp</dimen>
+
+    <dimen name="fab_margin">24dp</dimen>
+
+</resources>
--- a/app/src/main/res/values/attrs.xml
+++ b/app/src/main/res/values/attrs.xml
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<resources>
+    <declare-styleable name="ScrollChildSwipeRefreshLayout">
+        <attr name="refreshing" format="boolean" />
+    </declare-styleable>
+</resources>
--- a/app/src/main/res/values/colors.xml
+++ b/app/src/main/res/values/colors.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<resources>
+    <color name="colorPrimary">#FFFFF0</color>
+    <color name="colorPrimaryDark">#263238</color>
+    <color name="colorAccent">#2E7D32</color>
+    <color name="colorTextPrimary">#000000</color>
+    <color name="colorGrey">#757575</color>
+
+    <drawable name="completedTaskBackground">#CCCCCC</drawable>
+
+    <drawable name="touchFeedback">#CFD8DC</drawable>
+
+</resources>
--- a/app/src/main/res/values/dimens.xml
+++ b/app/src/main/res/values/dimens.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<resources>
+    <!-- Default screen margins, per the Android Design guidelines. -->
+    <dimen name="activity_horizontal_margin">16dp</dimen>
+    <dimen name="activity_vertical_margin">16dp</dimen>
+
+    <dimen name="fab_margin">16dp</dimen>
+
+    <dimen name="list_item_padding">8dp</dimen>
+    <dimen name="header_height">192dp</dimen>
+    <dimen name="header_padding">16dp</dimen>
+    <dimen name="header_image_width">100dp</dimen>
+
+</resources>
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<resources>
+    <string name="app_name">Todo</string>
+    <string name="add_task">New Task</string>
+    <string name="edit_task">Edit Task</string>
+    <string name="task_marked_complete">Task marked complete</string>
+    <string name="task_marked_active">Task marked active</string>
+    <string name="loading_tasks_error">Error while loading tasks</string>
+    <string name="completed_tasks_cleared">Completed tasks cleared</string>
+    <string name="menu_filter">Filter</string>
+    <string name="menu_clear">Clear completed</string>
+    <string name="menu_delete_task">Delete task</string>
+    <string name="navigation_view_header_title">Todo</string>
+    <string name="title_hint">Title</string>
+    <string name="description_hint">Enter your task here.</string>
+    <string name="empty_task_message">Tasks cannot be empty</string>
+    <string name="successfully_saved_task_message">Task saved</string>
+    <string name="list_title">Task List</string>
+    <string name="statistics_title">Statistics</string>
+    <string name="statistics_no_tasks">You have no tasks.</string>
+    <string name="statistics_active_tasks">Active tasks: %.1f%%</string>
+    <string name="statistics_completed_tasks">Completed tasks: %.1f%%</string>
+    <string name="statistics_error">Error loading statistics.</string>
+    <string name="no_data">No data</string>
+    <string name="loading">LOADING</string>
+
+    <string-array name="list_tasks_array">
+        <item>@string/nav_all</item>
+        <item>@string/nav_active</item>
+        <item>@string/nav_completed</item>
+    </string-array>
+    <string name="nav_all">All</string>
+    <string name="nav_active">Active</string>
+    <string name="nav_completed">Completed</string>
+    <string name="label_all">All Tasks</string>
+    <string name="label_active">Active Tasks</string>
+    <string name="label_completed">Completed Tasks</string>
+    <string name="no_tasks_all">You have no tasks!</string>
+    <string name="no_tasks_active">You have no active tasks!</string>
+    <string name="no_tasks_completed">You have no completed tasks!</string>
+    <string name="refresh">Refresh</string>
+    <string name="successfully_deleted_task_message">Task was deleted</string>
+    <string name="successfully_added_task_message">Task added</string>
+    <string name="no_data_description" />
+
+    <!-- Content Descriptions -->
+    <string name="tasks_header_image_content_description">Tasks header image</string>
+    <string name="no_tasks_image_content_description">No tasks image</string>
+
+</resources>
--- a/app/src/main/res/values/styles.xml
+++ b/app/src/main/res/values/styles.xml
+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright (C) 2019 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<resources xmlns:tools="http://schemas.android.com/tools">
+
+    <!-- Base application theme. --><style name="AppTheme" parent="Base.AppTheme" />
+
+    <style name="AppTheme.OverlapSystemBar" parent="Base.AppTheme" />
+
+    <style name="Base.AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
+        <!-- Customize your theme here. -->
+        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
+        <item name="colorAccent">@color/colorAccent</item>
+        <!-- For Android sdk versions 26+. -->
+        <item name="android:fontFamily" tools:targetApi="jelly_bean">@font/opensans_font</item>
+        <!-- Target Android sdk versions < 26 and > 14. -->
+        <item name="fontFamily">@font/opensans_font</item>
+        <!-- sets the style for the overflow button -->
+        <item name="actionOverflowButtonStyle">@style/actionOverflowButtonStyle</item>
+    </style>
+
+    <!-- This style defines the tint color of the overflow menu button -->
+    <style name="actionOverflowButtonStyle" parent="@style/Widget.AppCompat.ActionButton.Overflow">
+        <item name="android:tint">@color/colorAccent</item>
+    </style>
+
+    <style name="Toolbar" parent="ThemeOverlay.AppCompat.Light" />
+</resources>
--- a/app/src/mock/java/com/example/android/architecture/blueprints/todoapp/ServiceLocator.kt
+++ b/app/src/mock/java/com/example/android/architecture/blueprints/todoapp/ServiceLocator.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp
+
+import android.content.Context
+import androidx.annotation.VisibleForTesting
+import androidx.room.Room
+import com.example.android.architecture.blueprints.todoapp.data.FakeTasksRemoteDataSource
+import com.example.android.architecture.blueprints.todoapp.data.source.DefaultTasksRepository
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksDataSource
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksRepository
+import com.example.android.architecture.blueprints.todoapp.data.source.local.TasksLocalDataSource
+import com.example.android.architecture.blueprints.todoapp.data.source.local.ToDoDatabase
+import kotlinx.coroutines.runBlocking
+
+/**
+ * A Service Locator for the [TasksRepository]. This is the mock version, with a
+ * [FakeTasksRemoteDataSource].
+ */
+object ServiceLocator {
+
+    private val lock = Any()
+    private var database: ToDoDatabase? = null
+    @Volatile
+    var tasksRepository: TasksRepository? = null
+        @VisibleForTesting set
+
+    fun provideTasksRepository(context: Context): TasksRepository {
+        synchronized(this) {
+            return tasksRepository ?: tasksRepository ?: createTasksRepository(context)
+        }
+    }
+
+    private fun createTasksRepository(context: Context): TasksRepository {
+        val newRepo = DefaultTasksRepository(FakeTasksRemoteDataSource, createTaskLocalDataSource(context))
+        tasksRepository = newRepo
+        return newRepo
+    }
+
+    private fun createTaskLocalDataSource(context: Context): TasksDataSource {
+        val database = database ?: createDataBase(context)
+        return TasksLocalDataSource(database.taskDao())
+    }
+
+    private fun createDataBase(context: Context): ToDoDatabase {
+        val result = Room.databaseBuilder(
+            context.applicationContext,
+            ToDoDatabase::class.java, "Tasks.db"
+        ).build()
+        database = result
+        return result
+    }
+
+    @VisibleForTesting
+    fun resetRepository() {
+        synchronized(lock) {
+            runBlocking {
+                FakeTasksRemoteDataSource.deleteAllTasks()
+            }
+            // Clear all data to avoid test pollution.
+            database?.apply {
+                clearAllTables()
+                close()
+            }
+            database = null
+            tasksRepository = null
+        }
+    }
+}
--- a/app/src/mock/java/com/example/android/architecture/blueprints/todoapp/data/FakeTasksRemoteDataSource.kt
+++ b/app/src/mock/java/com/example/android/architecture/blueprints/todoapp/data/FakeTasksRemoteDataSource.kt
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.android.architecture.blueprints.todoapp.data
+
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.map
+import com.example.android.architecture.blueprints.todoapp.data.Result.Error
+import com.example.android.architecture.blueprints.todoapp.data.Result.Success
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksDataSource
+import java.util.LinkedHashMap
+
+/**
+ * Implementation of a remote data source with static access to the data for easy testing.
+ */
+object FakeTasksRemoteDataSource : TasksDataSource {
+
+    private var TASKS_SERVICE_DATA: LinkedHashMap<String, Task> = LinkedHashMap()
+
+    private val observableTasks = MutableLiveData<Result<List<Task>>>()
+
+    override suspend fun refreshTasks() {
+        observableTasks.postValue(getTasks())
+    }
+
+    override suspend fun refreshTask(taskId: String) {
+        refreshTasks()
+    }
+
+    override fun observeTasks(): LiveData<Result<List<Task>>> {
+        return observableTasks
+    }
+
+    override fun observeTask(taskId: String): LiveData<Result<Task>> {
+        return observableTasks.map { tasks ->
+            when (tasks) {
+                is Result.Loading -> Result.Loading
+                is Error -> Error(tasks.exception)
+                is Success -> {
+                    val task = tasks.data.firstOrNull() { it.id == taskId }
+                        ?: return@map Error(Exception("Not found"))
+                    Success(task)
+                }
+            }
+        }
+    }
+
+    override suspend fun getTask(taskId: String): Result<Task> {
+        TASKS_SERVICE_DATA[taskId]?.let {
+            return Success(it)
+        }
+        return Error(Exception("Could not find task"))
+    }
+
+    override suspend fun getTasks(): Result<List<Task>> {
+        return Success(TASKS_SERVICE_DATA.values.toList())
+    }
+
+    override suspend fun saveTask(task: Task) {
+        TASKS_SERVICE_DATA[task.id] = task
+    }
+
+    override suspend fun completeTask(task: Task) {
+        val completedTask = Task(task.title, task.description, true, task.id)
+        TASKS_SERVICE_DATA[task.id] = completedTask
+    }
+
+    override suspend fun completeTask(taskId: String) {
+        // Not required for the remote data source.
+    }
+
+    override suspend fun activateTask(task: Task) {
+        val activeTask = Task(task.title, task.description, false, task.id)
+        TASKS_SERVICE_DATA[task.id] = activeTask
+    }
+
+    override suspend fun activateTask(taskId: String) {
+        // Not required for the remote data source.
+    }
+
+    override suspend fun clearCompletedTasks() {
+        TASKS_SERVICE_DATA = TASKS_SERVICE_DATA.filterValues {
+            !it.isCompleted
+        } as LinkedHashMap<String, Task>
+    }
+
+    override suspend fun deleteTask(taskId: String) {
+        TASKS_SERVICE_DATA.remove(taskId)
+        refreshTasks()
+    }
+
+    override suspend fun deleteAllTasks() {
+        TASKS_SERVICE_DATA.clear()
+        refreshTasks()
+    }
+}
--- a/app/src/prod/java/com/example/android/architecture/blueprints/todoapp/ServiceLocator.kt
+++ b/app/src/prod/java/com/example/android/architecture/blueprints/todoapp/ServiceLocator.kt
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.architecture.blueprints.todoapp
+
+import android.content.Context
+import androidx.annotation.VisibleForTesting
+import androidx.room.Room
+import com.example.android.architecture.blueprints.todoapp.data.source.DefaultTasksRepository
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksDataSource
+import com.example.android.architecture.blueprints.todoapp.data.source.TasksRepository
+import com.example.android.architecture.blueprints.todoapp.data.source.local.TasksLocalDataSource
+import com.example.android.architecture.blueprints.todoapp.data.source.local.ToDoDatabase
+import com.example.android.architecture.blueprints.todoapp.data.source.remote.TasksRemoteDataSource
+import kotlinx.coroutines.runBlocking
+
+/**
+ * A Service Locator for the [TasksRepository]. This is the prod version, with a
+ * the "real" [TasksRemoteDataSource].
+ */
+object ServiceLocator {
+
+    private val lock = Any()
+    private var database: ToDoDatabase? = null
+    @Volatile
+    var tasksRepository: TasksRepository? = null
+        @VisibleForTesting set
+
+    fun provideTasksRepository(context: Context): TasksRepository {
+        synchronized(this) {
+            return tasksRepository ?: tasksRepository ?: createTasksRepository(context)
+        }
+    }
+
+    private fun createTasksRepository(context: Context): TasksRepository {
+        val newRepo =
+            DefaultTasksRepository(TasksRemoteDataSource, createTaskLocalDataSource(context))
+        tasksRepository = newRepo
+        return newRepo
+    }
+
+    private fun createTaskLocalDataSource(context: Context): TasksDataSource {
+        val database = database ?: createDataBase(context)
+        return TasksLocalDataSource(database.taskDao())
+    }
+
+    private fun createDataBase(context: Context): ToDoDatabase {
+        val result = Room.databaseBuilder(
+            context.applicationContext,
+            ToDoDatabase::class.java, DB_NAME
+        ).build()
+        database = result
+        return result
+    }
+
+    @VisibleForTesting
+    fun resetRepository() {
+        synchronized(lock) {
+            runBlocking {
+                TasksRemoteDataSource.deleteAllTasks()
+            }
+            // Clear all data to avoid test pollution.
+            database?.apply {
+                clearAllTables()
+                close()
+            }
+            database = null
+            tasksRepository = null
+        }
+    }
+}
+
+private const val DB_NAME = "Tasks.db"
--- a/app/src/prod/java/com/example/android/architecture/blueprints/todoapp/data/source/remote/TasksRemoteDataSource.kt
+++ b/app/src/prod/java/com/example/android/architecture/blueprints/todoapp/data/source/remote/TasksRemoteDataSource.kt
--- a/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/MainCoroutineRule.kt
+++ b/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/MainCoroutineRule.kt
--- a/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/addedittask/AddEditTaskFragmentTest.kt
+++ b/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/addedittask/AddEditTaskFragmentTest.kt
--- a/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/data/source/FakeRepository.kt
+++ b/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/data/source/FakeRepository.kt
--- a/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/data/source/local/TasksDaoTest.kt
+++ b/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/data/source/local/TasksDaoTest.kt
--- a/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/data/source/local/TasksLocalDataSourceTest.kt
+++ b/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/data/source/local/TasksLocalDataSourceTest.kt
--- a/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/statistics/StatisticsFragmentTest.kt
+++ b/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/statistics/StatisticsFragmentTest.kt
--- a/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/taskdetail/TaskDetailFragmentTest.kt
+++ b/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/taskdetail/TaskDetailFragmentTest.kt
--- a/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksFragmentTest.kt
+++ b/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksFragmentTest.kt
--- a/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/util/DataBindingIdlingResource.kt
+++ b/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/util/DataBindingIdlingResource.kt
--- a/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/util/TasksRepositoryExt.kt
+++ b/app/src/sharedTest/java/com/example/android/architecture/blueprints/todoapp/util/TasksRepositoryExt.kt
--- a/app/src/test/java/com/example/android/architecture/blueprints/todoapp/FakeFailingTasksRemoteDataSource.kt
+++ b/app/src/test/java/com/example/android/architecture/blueprints/todoapp/FakeFailingTasksRemoteDataSource.kt
--- a/app/src/test/java/com/example/android/architecture/blueprints/todoapp/LiveDataTestUtil.kt
+++ b/app/src/test/java/com/example/android/architecture/blueprints/todoapp/LiveDataTestUtil.kt
--- a/app/src/test/java/com/example/android/architecture/blueprints/todoapp/TestUtil.kt
+++ b/app/src/test/java/com/example/android/architecture/blueprints/todoapp/TestUtil.kt
--- a/app/src/test/java/com/example/android/architecture/blueprints/todoapp/addedittask/AddEditTaskViewModelTest.kt
+++ b/app/src/test/java/com/example/android/architecture/blueprints/todoapp/addedittask/AddEditTaskViewModelTest.kt
--- a/app/src/test/java/com/example/android/architecture/blueprints/todoapp/data/source/DefaultTasksRepositoryTest.kt
+++ b/app/src/test/java/com/example/android/architecture/blueprints/todoapp/data/source/DefaultTasksRepositoryTest.kt
--- a/app/src/test/java/com/example/android/architecture/blueprints/todoapp/data/source/FakeDataSource.kt
+++ b/app/src/test/java/com/example/android/architecture/blueprints/todoapp/data/source/FakeDataSource.kt
--- a/app/src/test/java/com/example/android/architecture/blueprints/todoapp/statistics/StatisticsUtilsTest.kt
+++ b/app/src/test/java/com/example/android/architecture/blueprints/todoapp/statistics/StatisticsUtilsTest.kt
--- a/app/src/test/java/com/example/android/architecture/blueprints/todoapp/statistics/StatisticsViewModelTest.kt
+++ b/app/src/test/java/com/example/android/architecture/blueprints/todoapp/statistics/StatisticsViewModelTest.kt
--- a/app/src/test/java/com/example/android/architecture/blueprints/todoapp/taskdetail/TaskDetailViewModelTest.kt
+++ b/app/src/test/java/com/example/android/architecture/blueprints/todoapp/taskdetail/TaskDetailViewModelTest.kt
--- a/app/src/test/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksViewModelTest.kt
+++ b/app/src/test/java/com/example/android/architecture/blueprints/todoapp/tasks/TasksViewModelTest.kt
--- a/app/src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker
+++ b/app/src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker
--- a/build.gradle
+++ b/build.gradle
--- a/gradle.properties
+++ b/gradle.properties
--- a/gradle/wrapper/gradle-wrapper.jar
+++ b/gradle/wrapper/gradle-wrapper.jar
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
--- a/gradlew
+++ b/gradlew
--- a/gradlew.bat
+++ b/gradlew.bat
--- a/settings.gradle
+++ b/settings.gradle