frist commit

.gitignore

@@ -0,0 +1,9 @@
+*.iml
+.gradle
+/local.properties
+/.idea
+.DS_Store
+/build
+/captures
+.externalNativeBuild
+local.properties

CONTRIBUTING.md

@@ -0,0 +1,28 @@
+# How to Contribute
+
+We'd love to accept your patches and contributions to this project. There are
+just a few small guidelines you need to follow.
+
+## Contributor License Agreement
+
+Contributions to this project must be accompanied by a Contributor License
+Agreement. You (or your employer) retain the copyright to your contribution,
+this simply gives us permission to use and redistribute your contributions as
+part of the project. Head over to <https://cla.developers.google.com/> to see
+your current agreements on file or to sign a new one.
+
+You generally only need to submit a CLA once, so if you've already submitted one
+(even if it was for a different project), you probably don't need to do it
+again.
+
+## Code reviews
+
+All submissions, including submissions by project members, require review. We
+use GitHub pull requests for this purpose. Consult
+[GitHub Help](https://help.github.com/articles/about-pull-requests/) for more
+information on using pull requests.
+
+## Community Guidelines
+
+This project follows [Google's Open Source Community
+Guidelines](https://opensource.google.com/conduct/).

LICENSE

@@ -0,0 +1,201 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
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+   6. Trademarks. This License does not grant permission to use the trade
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+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
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+   Copyright 2014 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.

README.md

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+# Using State in Jetpack Compose Codelab
+
+This folder contains the source code for the [Using State in Jetpack Compose codelab](https://developer.android.com/codelabs/jetpack-compose-state).
+
+
+In this codelab, you will explore patterns for working with state in a declarative world by building a Todo application. We'll see what unidirectional
+data flow is, and how to apply it in a Jetpack Compose application to build stateless and stateful composables.
+
+## Screenshots
+
+![Finished code](screenshots/state_movie.gif "After: Animation of fully completed project")
+
+## License
+
+```
+Copyright 2020 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
+
+    https://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.
+```

build.gradle

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+/*
+ * Copyright (C) 2020 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.
+ */
+
+// Top-level build file where you can add configuration options common to all sub-projects/modules.
+buildscript {
+    ext {
+        compose_version = '1.1.1'
+        activity_compose_version = '1.4.0'
+        viewmodel_compose_version = '2.4.0'
+        kotlin_version = '1.6.10'
+    }
+    repositories {
+        google()
+        mavenCentral()
+    }
+    dependencies {
+        classpath 'com.android.tools.build:gradle:7.1.2'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+allprojects {
+    repositories {
+        google()
+        mavenCentral()
+    }
+}

finished/.gitignore

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+/build

finished/build.gradle

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+/*
+ * Copyright (C) 2020 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.
+ */
+
+plugins {
+    id 'com.android.application'
+    id 'kotlin-android'
+}
+
+android {
+    compileSdkVersion 31
+
+    defaultConfig {
+        applicationId "com.example.statecodelab"
+        minSdkVersion 21
+        targetSdkVersion 31
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+        useIR = true
+        allWarningsAsErrors = true
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    buildFeatures {
+        compose true
+    }
+    composeOptions {
+        kotlinCompilerExtensionVersion "$compose_version"
+    }
+}
+
+dependencies {
+
+    implementation 'androidx.core:core-ktx:1.7.0'
+    implementation 'androidx.appcompat:appcompat:1.3.1'
+    implementation 'com.google.android.material:material:1.4.0'
+    implementation "androidx.fragment:fragment-ktx:1.3.6"
+    implementation "androidx.activity:activity-compose:$activity_compose_version"
+    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.4.0"
+    implementation "androidx.lifecycle:lifecycle-viewmodel-savedstate:2.4.0"
+    implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.4.0"
+    implementation "androidx.lifecycle:lifecycle-viewmodel-compose:$viewmodel_compose_version"
+
+    implementation "androidx.compose.animation:animation:$compose_version"
+    implementation "androidx.compose.foundation:foundation:$compose_version"
+    implementation "androidx.compose.foundation:foundation-layout:$compose_version"
+    implementation "androidx.compose.material:material:$compose_version"
+    implementation "androidx.compose.material:material-icons-extended:$compose_version"
+    implementation "androidx.compose.runtime:runtime-livedata:$compose_version"
+    implementation "androidx.compose.runtime:runtime:$compose_version"
+    implementation "androidx.compose.ui:ui:$compose_version"
+    implementation "androidx.compose.ui:ui-tooling-preview:$compose_version"
+    debugImplementation "androidx.compose.ui:ui-tooling:$compose_version"
+
+    testImplementation 'junit:junit:4.13.2'
+    testImplementation "com.google.truth:truth:1.1.2"
+    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
+}
+
+// Compiler flag to use experimental Compose APIs
+tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).configureEach {
+    kotlinOptions {
+        jvmTarget = "1.8"
+        freeCompilerArgs += [
+                "-Xopt-in=kotlin.RequiresOptIn"
+        ]
+    }
+}

finished/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 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.codelabs.state">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:supportsRtl="true"
+        android:exported="true"
+        android:theme="@style/Theme.StateCodelab">
+        <activity
+            android:name="com.codelabs.state.todo.TodoActivity"
+            android:label="@string/app_name"
+            android:exported="true"
+            android:theme="@style/Theme.StateCodelab.NoActionBar">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

finished/src/main/java/com/codelabs/state/todo/Data.kt

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+/*
+ * Copyright (C) 2020 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.codelabs.state.todo
+
+import androidx.annotation.StringRes
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.CropSquare
+import androidx.compose.material.icons.filled.Done
+import androidx.compose.material.icons.filled.Event
+import androidx.compose.material.icons.filled.PrivacyTip
+import androidx.compose.material.icons.filled.RestoreFromTrash
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.res.stringResource
+import com.codelabs.state.R
+import java.util.UUID
+
+data class TodoItem(
+    val task: String,
+    val icon: TodoIcon = TodoIcon.Default,
+    // since the user may generate identical tasks, give them each a unique ID
+    val id: UUID = UUID.randomUUID()
+)
+
+enum class TodoIcon(val imageVector: ImageVector, @StringRes val contentDescription: Int) {
+    Square(Icons.Default.CropSquare, R.string.cd_crop_square),
+    Done(Icons.Default.Done, R.string.cd_done),
+    Event(Icons.Default.Event, R.string.cd_event),
+    Privacy(Icons.Default.PrivacyTip, R.string.cd_privacy),
+    Trash(Icons.Default.RestoreFromTrash, R.string.cd_restore);
+
+    companion object {
+        val Default = Square
+    }
+}

finished/src/main/java/com/codelabs/state/todo/TodoActivity.kt

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.todo
+
+import android.os.Bundle
+import androidx.activity.compose.setContent
+import androidx.activity.viewModels
+import androidx.appcompat.app.AppCompatActivity
+import androidx.compose.material.Surface
+import androidx.compose.runtime.Composable
+import com.codelabs.state.ui.StateCodelabTheme
+
+class TodoActivity : AppCompatActivity() {
+
+    val todoViewModel by viewModels<TodoViewModel>()
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContent {
+            StateCodelabTheme {
+                Surface {
+                    TodoActivityScreen(todoViewModel)
+                }
+            }
+        }
+    }
+}
+
+@Composable
+private fun TodoActivityScreen(todoViewModel: TodoViewModel) {
+    TodoScreen(
+        items = todoViewModel.todoItems,
+        currentlyEditing = todoViewModel.currentEditItem,
+        onAddItem = todoViewModel::addItem,
+        onRemoveItem = todoViewModel::removeItem,
+        onStartEdit = todoViewModel::onEditItemSelected,
+        onEditItemChange = todoViewModel::onEditItemChange,
+        onEditDone = todoViewModel::onEditDone
+    )
+}

finished/src/main/java/com/codelabs/state/todo/TodoComponents.kt

@@ -0,0 +1,254 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.todo
+
+import androidx.annotation.StringRes
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.ExperimentalAnimationApi
+import androidx.compose.animation.animateContentSize
+import androidx.compose.animation.core.FastOutLinearInEasing
+import androidx.compose.animation.core.FastOutSlowInEasing
+import androidx.compose.animation.core.TweenSpec
+import androidx.compose.animation.core.animateDpAsState
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.RowScope
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.defaultMinSize
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.foundation.text.KeyboardActions
+import androidx.compose.foundation.text.KeyboardOptions
+import androidx.compose.material.Icon
+import androidx.compose.material.MaterialTheme
+import androidx.compose.material.Surface
+import androidx.compose.material.Text
+import androidx.compose.material.TextButton
+import androidx.compose.material.TextField
+import androidx.compose.material.TextFieldDefaults
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.remember
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.RectangleShape
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.platform.LocalSoftwareKeyboardController
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.input.ImeAction
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+
+/**
+ * Draws a row of [TodoIcon] with visibility changes animated.
+ *
+ * When not visible, will collapse to 16.dp high by default. You can enlarge this with the passed
+ * modifier.
+ *
+ * @param icon (state) the current selected icon
+ * @param onIconChange (event) request the selected icon change
+ * @param modifier modifier for this element
+ * @param visible (state) if the icon should be shown
+ */
+@OptIn(ExperimentalAnimationApi::class)
+@Composable
+fun AnimatedIconRow(
+    icon: TodoIcon,
+    onIconChange: (TodoIcon) -> Unit,
+    modifier: Modifier = Modifier,
+    visible: Boolean = true,
+) {
+    // remember these specs so they don't restart if recomposing during the animation
+    // this is required since TweenSpec restarts on interruption
+    val enter = remember { fadeIn(animationSpec = TweenSpec(300, easing = FastOutLinearInEasing)) }
+    val exit = remember { fadeOut(animationSpec = TweenSpec(100, easing = FastOutSlowInEasing)) }
+    Box(modifier.defaultMinSize(minHeight = 16.dp)) {
+        AnimatedVisibility(
+            visible = visible,
+            enter = enter,
+            exit = exit,
+        ) {
+            IconRow(icon, onIconChange)
+        }
+    }
+}
+
+/**
+ * Displays a row of selectable [TodoIcon]
+ *
+ * @param icon (state) the current selected icon
+ * @param onIconChange (event) request the selected icon change
+ * @param modifier modifier for this element
+ */
+@Composable
+fun IconRow(
+    icon: TodoIcon,
+    onIconChange: (TodoIcon) -> Unit,
+    modifier: Modifier = Modifier
+) {
+    Row(modifier) {
+        for (todoIcon in TodoIcon.values()) {
+            SelectableIconButton(
+                icon = todoIcon.imageVector,
+                iconContentDescription = todoIcon.contentDescription,
+                onIconSelected = { onIconChange(todoIcon) },
+                isSelected = todoIcon == icon
+            )
+        }
+    }
+}
+
+/**
+ * Displays a single icon that can be selected.
+ *
+ * @param icon the icon to draw
+ * @param onIconSelected (event) request this icon be selected
+ * @param isSelected (state) selection state
+ * @param modifier modifier for this element
+ */
+@Composable
+private fun SelectableIconButton(
+    icon: ImageVector,
+    @StringRes iconContentDescription: Int,
+    onIconSelected: () -> Unit,
+    isSelected: Boolean,
+    modifier: Modifier = Modifier
+) {
+    val tint = if (isSelected) {
+        MaterialTheme.colors.primary
+    } else {
+        MaterialTheme.colors.onSurface.copy(alpha = 0.6f)
+    }
+    TextButton(
+        onClick = { onIconSelected() },
+        shape = CircleShape,
+        modifier = modifier
+    ) {
+        Column {
+            Icon(
+                imageVector = icon,
+                tint = tint,
+                contentDescription = stringResource(id = iconContentDescription)
+            )
+            if (isSelected) {
+                Box(
+                    Modifier
+                        .padding(top = 3.dp)
+                        .width(icon.defaultWidth)
+                        .height(1.dp)
+                        .background(tint)
+                )
+            } else {
+                Spacer(modifier = Modifier.height(4.dp))
+            }
+        }
+    }
+}
+
+/**
+ * Draw a background based on [MaterialTheme.colors.onSurface] that animates resizing and elevation
+ * changes.
+ *
+ * @param elevate draw a shadow, changes to this will be animated
+ * @param modifier modifier for this element
+ * @param content (slot) content to draw in the background
+ */
+@Composable
+fun TodoItemInputBackground(
+    elevate: Boolean,
+    modifier: Modifier = Modifier,
+    content: @Composable RowScope.() -> Unit
+) {
+    val animatedElevation by animateDpAsState(if (elevate) 1.dp else 0.dp, TweenSpec(500))
+    Surface(
+        color = MaterialTheme.colors.onSurface.copy(alpha = 0.05f),
+        elevation = animatedElevation,
+        shape = RectangleShape,
+    ) {
+        Row(
+            modifier = modifier.animateContentSize(animationSpec = TweenSpec(300)),
+            content = content
+        )
+    }
+}
+
+/**
+ * Styled [TextField] for inputting a [TodoItem].
+ *
+ * @param text (state) current text to display
+ * @param onTextChange (event) request the text change state
+ * @param modifier the modifier for this element
+ * @param onImeAction (event) notify caller of [ImeAction.Done] events
+ */
+@OptIn(ExperimentalComposeUiApi::class)
+@Composable
+fun TodoInputText(
+    text: String,
+    onTextChange: (String) -> Unit,
+    modifier: Modifier = Modifier,
+    onImeAction: () -> Unit = {}
+) {
+    val keyboardController = LocalSoftwareKeyboardController.current
+    TextField(
+        value = text,
+        onValueChange = onTextChange,
+        colors = TextFieldDefaults.textFieldColors(backgroundColor = Color.Transparent),
+        maxLines = 1,
+        keyboardOptions = KeyboardOptions.Default.copy(imeAction = ImeAction.Done),
+        keyboardActions = KeyboardActions(onDone = {
+            onImeAction()
+            keyboardController?.hide()
+        }),
+        modifier = modifier
+    )
+}
+
+/**
+ * Styled button for [TodoScreen]
+ *
+ * @param onClick (event) notify caller of click events
+ * @param text button text
+ * @param modifier modifier for button
+ * @param enabled enable or disable the button
+ */
+@Composable
+fun TodoEditButton(
+    onClick: () -> Unit,
+    text: String,
+    modifier: Modifier = Modifier,
+    enabled: Boolean = true
+) {
+    TextButton(
+        onClick = onClick,
+        shape = CircleShape,
+        enabled = enabled,
+        modifier = modifier
+    ) {
+        Text(text)
+    }
+}
+
+@Preview
+@Composable
+fun PreviewIconRow() = IconRow(icon = TodoIcon.Square, onIconChange = {})

finished/src/main/java/com/codelabs/state/todo/TodoScreen.kt

@@ -0,0 +1,311 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.todo
+
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.IntrinsicSize
+import androidx.compose.foundation.layout.PaddingValues
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.layout.widthIn
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.items
+import androidx.compose.material.Button
+import androidx.compose.material.Icon
+import androidx.compose.material.LocalContentColor
+import androidx.compose.material.MaterialTheme
+import androidx.compose.material.Text
+import androidx.compose.material.TextButton
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.saveable.rememberSaveable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import com.codelabs.state.util.generateRandomTodoItem
+import kotlin.random.Random
+
+/**
+ * Stateless component that is responsible for the entire todo screen.
+ *
+ * @param items (state) list of [TodoItem] to display
+ * @param currentlyEditing (state) enable edit mode for this item
+ * @param onAddItem (event) request an item be added
+ * @param onRemoveItem (event) request an item be removed
+ * @param onStartEdit (event) request an item start edit mode
+ * @param onEditItemChange (event) request the current edit item be updated
+ * @param onEditDone (event) request edit mode completion
+ */
+@Composable
+fun TodoScreen(
+    items: List<TodoItem>,
+    currentlyEditing: TodoItem?,
+    onAddItem: (TodoItem) -> Unit,
+    onRemoveItem: (TodoItem) -> Unit,
+    onStartEdit: (TodoItem) -> Unit,
+    onEditItemChange: (TodoItem) -> Unit,
+    onEditDone: () -> Unit
+) {
+    Column {
+        val enableTopSection = currentlyEditing == null
+        TodoItemInputBackground(elevate = enableTopSection) {
+            if (enableTopSection) {
+                TodoItemEntryInput(onAddItem)
+            } else {
+                Text(
+                    text = "Editing item",
+                    style = MaterialTheme.typography.h6,
+                    textAlign = TextAlign.Center,
+                    modifier = Modifier
+                        .align(Alignment.CenterVertically)
+                        .padding(16.dp)
+                        .fillMaxWidth()
+                )
+            }
+        }
+
+        LazyColumn(
+            modifier = Modifier.weight(1f),
+            contentPadding = PaddingValues(top = 8.dp)
+        ) {
+            items(items = items) { todo ->
+                if (currentlyEditing?.id == todo.id) {
+                    TodoItemInlineEditor(
+                        item = currentlyEditing,
+                        onEditItemChange = onEditItemChange,
+                        onEditDone = onEditDone,
+                        onRemoveItem = { onRemoveItem(todo) }
+                    )
+                } else {
+                    TodoRow(
+                        todo = todo,
+                        onItemClicked = { onStartEdit(it) },
+                        modifier = Modifier.fillParentMaxWidth()
+                    )
+                }
+            }
+        }
+
+        // For quick testing, a random item generator button
+        Button(
+            onClick = { onAddItem(generateRandomTodoItem()) },
+            modifier = Modifier
+                .padding(16.dp)
+                .fillMaxWidth(),
+        ) {
+            Text("Add random item")
+        }
+    }
+}
+
+/**
+ * Stateless composable that provides a styled [TodoItemInput] for inline editing.
+ *
+ * This composable will display a floppy disk and ❌ for the buttons.
+ *
+ * @param item (state) the current item to display in editor
+ * @param onEditItemChange (event) request item be changed
+ * @param onEditDone (event) request edit mode completion for this item
+ * @param onRemoveItem (event) request this item be removed
+ */
+@Composable
+fun TodoItemInlineEditor(
+    item: TodoItem,
+    onEditItemChange: (TodoItem) -> Unit,
+    onEditDone: () -> Unit,
+    onRemoveItem: () -> Unit
+) {
+    TodoItemInput(
+        text = item.task,
+        onTextChange = { onEditItemChange(item.copy(task = it)) },
+        icon = item.icon,
+        onIconChange = { onEditItemChange(item.copy(icon = it)) },
+        submit = onEditDone,
+        iconsVisible = true,
+        buttonSlot = {
+            Row {
+                val shrinkButtons = Modifier.widthIn(20.dp)
+                TextButton(onClick = onEditDone, modifier = shrinkButtons) {
+                    Text(
+                        "\uD83D\uDCBE", // floppy disk
+                        textAlign = TextAlign.End,
+                        modifier = Modifier.width(30.dp)
+                    )
+                }
+                TextButton(onClick = onRemoveItem, modifier = shrinkButtons) {
+                    Text(
+                        "❌",
+                        textAlign = TextAlign.End,
+                        modifier = Modifier.width(30.dp)
+                    )
+                }
+            }
+        }
+    )
+}
+
+/**
+ * Stateful composable to allow entry of *new* [TodoItem].
+ *
+ * This composable will display a button with [buttonText].
+ *
+ * @param onItemComplete (event) notify the caller that the user has completed entry of an item
+ * @param buttonText text to display on the button
+ */
+@Composable
+fun TodoItemEntryInput(onItemComplete: (TodoItem) -> Unit, buttonText: String = "Add") {
+    val (text, onTextChange) = rememberSaveable { mutableStateOf("") }
+    val (icon, onIconChange) = remember { mutableStateOf(TodoIcon.Default) }
+
+    val submit = {
+        if (text.isNotBlank()) {
+            onItemComplete(TodoItem(text, icon))
+            onTextChange("")
+            onIconChange(TodoIcon.Default)
+        }
+    }
+
+    TodoItemInput(
+        text = text,
+        onTextChange = onTextChange,
+        icon = icon,
+        onIconChange = onIconChange,
+        submit = submit,
+        iconsVisible = text.isNotBlank()
+    ) {
+        TodoEditButton(onClick = submit, text = buttonText, enabled = text.isNotBlank())
+    }
+}
+
+/**
+ * Stateless input composable for editing [TodoItem].
+ *
+ * @param text (state) current text of the item
+ * @param onTextChange (event) request the text change
+ * @param icon (state) current selected icon for the item
+ * @param onIconChange (event) request the current icon change
+ * @param submit (event) notify the caller that the user has submitted with [ImeAction.Done]
+ * @param iconsVisible (state) display icons or hide them
+ * @param buttonSlot (slot) slot for providing buttons next to the text
+ */
+@Composable
+fun TodoItemInput(
+    text: String,
+    onTextChange: (String) -> Unit,
+    icon: TodoIcon,
+    onIconChange: (TodoIcon) -> Unit,
+    submit: () -> Unit,
+    iconsVisible: Boolean,
+    buttonSlot: @Composable () -> Unit,
+) {
+    Column {
+        Row(
+            Modifier
+                .padding(horizontal = 16.dp)
+                .padding(top = 16.dp)
+                .height(IntrinsicSize.Min)
+        ) {
+            TodoInputText(
+                text = text,
+                onTextChange = onTextChange,
+                modifier = Modifier
+                    .weight(1f)
+                    .padding(end = 8.dp),
+                onImeAction = submit
+            )
+            Spacer(modifier = Modifier.width(8.dp))
+            Box(Modifier.align(Alignment.CenterVertically)) { buttonSlot() }
+        }
+        if (iconsVisible) {
+            AnimatedIconRow(
+                icon = icon,
+                onIconChange = onIconChange,
+                modifier = Modifier.padding(top = 8.dp),
+            )
+        } else {
+            Spacer(Modifier.height(16.dp))
+        }
+    }
+}
+
+/**
+ * Stateless composable that displays a full-width [TodoItem].
+ *
+ * @param todo item to show
+ * @param onItemClicked (event) notify caller that the row was clicked
+ * @param modifier modifier for this element
+ * @param iconAlpha alpha tint to apply to icon, by default random between 0.3 and 0.9
+ */
+@Composable
+fun TodoRow(
+    todo: TodoItem,
+    onItemClicked: (TodoItem) -> Unit,
+    modifier: Modifier = Modifier,
+    iconAlpha: Float = remember(todo.id) { randomTint() }
+) {
+    Row(
+        modifier
+            .clickable { onItemClicked(todo) }
+            .padding(horizontal = 16.dp, vertical = 8.dp),
+        horizontalArrangement = Arrangement.SpaceBetween
+    ) {
+        Text(todo.task)
+        Icon(
+            imageVector = todo.icon.imageVector,
+            tint = LocalContentColor.current.copy(alpha = iconAlpha),
+            contentDescription = stringResource(id = todo.icon.contentDescription)
+        )
+    }
+}
+
+private fun randomTint(): Float {
+    return Random.nextFloat().coerceIn(0.3f, 0.9f)
+}
+
+@Preview
+@Composable
+fun PreviewTodoScreen() {
+    val items = listOf(
+        TodoItem("Learn compose", TodoIcon.Event),
+        TodoItem("Take the codelab"),
+        TodoItem("Apply state", TodoIcon.Done),
+        TodoItem("Build dynamic UIs", TodoIcon.Square)
+    )
+    TodoScreen(items, null, {}, {}, {}, {}, {})
+}
+
+@Preview
+@Composable
+fun PreviewTodoItemInput() = TodoItemEntryInput(onItemComplete = { })
+
+@Preview
+@Composable
+fun PreviewTodoRow() {
+    val todo = remember { generateRandomTodoItem() }
+    TodoRow(todo = todo, onItemClicked = {}, modifier = Modifier.fillMaxWidth())
+}

finished/src/main/java/com/codelabs/state/todo/TodoViewModel.kt

@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.todo
+
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateListOf
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.lifecycle.ViewModel
+
+class TodoViewModel : ViewModel() {
+
+    private var currentEditPosition by mutableStateOf(-1)
+
+    var todoItems = mutableStateListOf<TodoItem>()
+        private set
+
+    val currentEditItem: TodoItem?
+        get() = todoItems.getOrNull(currentEditPosition)
+
+    fun addItem(item: TodoItem) {
+        todoItems.add(item)
+    }
+
+    fun removeItem(item: TodoItem) {
+        todoItems.remove(item)
+        onEditDone() // don't keep the editor open when removing items
+    }
+
+    fun onEditItemSelected(item: TodoItem) {
+        currentEditPosition = todoItems.indexOf(item)
+    }
+
+    fun onEditDone() {
+        currentEditPosition = -1
+    }
+
+    fun onEditItemChange(item: TodoItem) {
+        val currentItem = requireNotNull(currentEditItem)
+        require(currentItem.id == item.id) {
+            "You can only change an item with the same id as currentEditItem"
+        }
+
+        todoItems[currentEditPosition] = item
+    }
+}

finished/src/main/java/com/codelabs/state/ui/Color.kt

@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.ui
+
+import androidx.compose.ui.graphics.Color
+
+val purple200 = Color(0xFFBB86FC)
+val purple500 = Color(0xFF6200EE)
+val purple700 = Color(0xFF3700B3)
+val teal200 = Color(0xFF03DAC5)

finished/src/main/java/com/codelabs/state/ui/Shape.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.ui
+
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material.Shapes
+import androidx.compose.ui.unit.dp
+
+val shapes = Shapes(
+    small = RoundedCornerShape(4.dp),
+    medium = RoundedCornerShape(4.dp),
+    large = RoundedCornerShape(0.dp)
+)

finished/src/main/java/com/codelabs/state/ui/Theme.kt

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.ui
+
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.material.MaterialTheme
+import androidx.compose.material.darkColors
+import androidx.compose.material.lightColors
+import androidx.compose.runtime.Composable
+
+private val DarkColorPalette = darkColors(
+    primary = purple200,
+    primaryVariant = purple700,
+    secondary = teal200
+)
+
+private val LightColorPalette = lightColors(
+    primary = purple500,
+    primaryVariant = purple700,
+    secondary = teal200
+)
+
+@Composable
+fun StateCodelabTheme(
+    darkTheme: Boolean = isSystemInDarkTheme(),
+    content: @Composable() () -> Unit
+) {
+    val colors = if (darkTheme) {
+        DarkColorPalette
+    } else {
+        LightColorPalette
+    }
+
+    MaterialTheme(
+        colors = colors,
+        typography = typography,
+        shapes = shapes,
+        content = content
+    )
+}

finished/src/main/java/com/codelabs/state/ui/Type.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.ui
+
+import androidx.compose.material.Typography
+import androidx.compose.ui.text.TextStyle
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.sp
+
+// Set of Material typography styles to start with
+val typography = Typography(
+    body1 = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Normal,
+        fontSize = 16.sp
+    )
+)

finished/src/main/java/com/codelabs/state/util/DataGenerators.kt

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.util
+
+import com.codelabs.state.todo.TodoIcon
+import com.codelabs.state.todo.TodoItem
+
+fun generateRandomTodoItem(): TodoItem {
+    val message = listOf(
+        "Learn compose",
+        "Learn state",
+        "Build dynamic UIs",
+        "Learn Unidirectional Data Flow",
+        "Integrate LiveData",
+        "Integrate ViewModel",
+        "Remember to savedState!",
+        "Build stateless composables",
+        "Use state from stateless composables"
+    ).random()
+    val icon = TodoIcon.values().random()
+    return TodoItem(message, icon)
+}

finished/src/main/res/drawable/ic_launcher_background.xml

@@ -0,0 +1,186 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 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="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path
+        android:fillColor="#3DDC84"
+        android:pathData="M0,0h108v108h-108z" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M9,0L9,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,0L19,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,0L29,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,0L39,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,0L49,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,0L59,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,0L69,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,0L79,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M89,0L89,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M99,0L99,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,9L108,9"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,19L108,19"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,29L108,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,39L108,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,49L108,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,59L108,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,69L108,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,79L108,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,89L108,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,99L108,99"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,29L89,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,39L89,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,49L89,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,59L89,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,69L89,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,79L89,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,19L29,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,19L39,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,19L49,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,19L59,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,19L69,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,19L79,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+</vector>

finished/src/main/res/values-night/themes.xml

@@ -0,0 +1,32 @@
+<!--
+  ~ Copyright (C) 2020 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="Theme.StateCodelab" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
+        <!-- Primary brand color. -->
+        <item name="colorPrimary">@color/purple_200</item>
+        <item name="colorPrimaryVariant">@color/purple_700</item>
+        <item name="colorOnPrimary">@color/black</item>
+        <!-- Secondary brand color. -->
+        <item name="colorSecondary">@color/teal_200</item>
+        <item name="colorSecondaryVariant">@color/teal_200</item>
+        <item name="colorOnSecondary">@color/black</item>
+        <!-- Status bar color. -->
+        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>
+        <!-- Customize your theme here. -->
+    </style>
+</resources>

finished/src/main/res/values/colors.xml

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 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="purple_200">#FFBB86FC</color>
+    <color name="purple_500">#FF6200EE</color>
+    <color name="purple_700">#FF3700B3</color>
+    <color name="teal_200">#FF03DAC5</color>
+    <color name="teal_700">#FF018786</color>
+    <color name="black">#FF000000</color>
+    <color name="white">#FFFFFFFF</color>
+</resources>

finished/src/main/res/values/strings.xml

@@ -0,0 +1,24 @@
+<!--
+  ~ Copyright (C) 2020 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">
+    <string name="app_name">StateCodelab</string>
+    <string name="cd_crop_square" tools:ignore="ExtraTranslation">Crop</string>
+    <string name="cd_done">Done</string>
+    <string name="cd_event">Event</string>
+    <string name="cd_privacy">Privacy</string>
+    <string name="cd_restore">Restore</string>
+</resources>

finished/src/main/res/values/themes.xml

@@ -0,0 +1,37 @@
+<!--
+  ~ Copyright (C) 2020 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="Theme.StateCodelab" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
+        <!-- Primary brand color. -->
+        <item name="colorPrimary">@color/purple_500</item>
+        <item name="colorPrimaryVariant">@color/purple_700</item>
+        <item name="colorOnPrimary">@color/white</item>
+        <!-- Secondary brand color. -->
+        <item name="colorSecondary">@color/teal_200</item>
+        <item name="colorSecondaryVariant">@color/teal_700</item>
+        <item name="colorOnSecondary">@color/black</item>
+        <!-- Status bar color. -->
+        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>
+        <!-- Customize your theme here. -->
+    </style>
+
+    <style name="Theme.StateCodelab.NoActionBar">
+        <item name="windowActionBar">false</item>
+        <item name="windowNoTitle">true</item>
+    </style>
+</resources>

finished/src/test/java/com/codelabs/state/todo/TodoViewModelTest.kt

@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.todo
+
+import com.codelabs.state.util.generateRandomTodoItem
+import com.google.common.truth.Truth.assertThat
+import org.junit.Test
+
+class TodoViewModelTest {
+
+    @Test
+    fun whenAddItem_updatesList() {
+        val subject = TodoViewModel()
+        val expected = generateRandomTodoItem()
+        subject.addItem(expected)
+        assertThat(subject.todoItems).isEqualTo(listOf(expected))
+    }
+
+    @Test
+    fun whenRemovingItem_updatesList() {
+        val subject = TodoViewModel()
+        val item1 = generateRandomTodoItem()
+        val item2 = generateRandomTodoItem()
+        subject.addItem(item1)
+        subject.addItem(item2)
+        subject.removeItem(item1)
+        assertThat(subject.todoItems).isEqualTo(listOf(item2))
+    }
+
+    @Test
+    fun whenNotEditing_currentEditItemIsNull() {
+        val subject = TodoViewModel()
+        val item = generateRandomTodoItem()
+        subject.addItem(item)
+        assertThat(subject.currentEditItem).isNull()
+    }
+
+    @Test
+    fun whenEditing_currentEditItemIsCorrectItem() {
+        val subject = TodoViewModel()
+        val item1 = generateRandomTodoItem()
+        val item2 = generateRandomTodoItem()
+        subject.addItem(item1)
+        subject.addItem(item2)
+        subject.onEditItemSelected(item1)
+        assertThat(subject.currentEditItem).isEqualTo(item1)
+    }
+
+    @Test
+    fun whenEditingDone_currentEditItemIsCorrectItem() {
+        val subject = TodoViewModel()
+        val item1 = generateRandomTodoItem()
+        val item2 = generateRandomTodoItem()
+        subject.addItem(item1)
+        subject.addItem(item2)
+        subject.onEditItemSelected(item1)
+        subject.onEditDone()
+        assertThat(subject.currentEditItem).isNull()
+    }
+
+    @Test
+    fun whenEditingItem_updatesAreShownInItemAndList() {
+        val subject = TodoViewModel()
+        val item1 = generateRandomTodoItem()
+        val item2 = generateRandomTodoItem()
+        subject.addItem(item1)
+        subject.addItem(item2)
+        subject.onEditItemSelected(item1)
+        val expected = item1.copy(task = "Update for test case")
+        subject.onEditItemChange(expected)
+        assertThat(subject.todoItems).isEqualTo(listOf(expected, item2))
+        assertThat(subject.currentEditItem).isEqualTo(expected)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun whenEditing_wrongItemThrows() {
+        val subject = TodoViewModel()
+        val item1 = generateRandomTodoItem()
+        val item2 = generateRandomTodoItem()
+        subject.addItem(item1)
+        subject.addItem(item2)
+        subject.onEditItemSelected(item1)
+        val expected = item2.copy(task = "Update for test case")
+        subject.onEditItemChange(expected)
+    }
+
+    @Test(expected = IllegalArgumentException::class)
+    fun whenNotEditing_onEditItemChangeThrows() {
+        val subject = TodoViewModel()
+        val item = generateRandomTodoItem()
+        subject.onEditItemChange(item)
+    }
+}

gradle.properties

@@ -0,0 +1,37 @@
+#
+# Copyright (C) 2020 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.
+#
+
+# Project-wide Gradle settings.
+# IDE (e.g. Android Studio) users:
+# Gradle settings configured through the IDE *will override*
+# any settings specified in this file.
+# For more details on how to configure your build environment visit
+# http://www.gradle.org/docs/current/userguide/build_environment.html
+# Specifies the JVM arguments used for the daemon process.
+# The setting is particularly useful for tweaking memory settings.
+org.gradle.jvmargs=-Xmx2048m -Dfile.encoding=UTF-8
+# When configured, Gradle will run in incubating parallel mode.
+# This option should only be used with decoupled projects. More details, visit
+# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
+# org.gradle.parallel=true
+# AndroidX package structure to make it clearer which packages are bundled with the
+# Android operating system, and which are packaged with your app"s APK
+# https://developer.android.com/topic/libraries/support-library/androidx-rn
+android.useAndroidX=true
+# Automatically convert third-party libraries to use AndroidX
+android.enableJetifier=true
+# Kotlin code style for this project: "official" or "obsolete":
+kotlin.code.style=official

gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.2-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists

gradlew

@@ -0,0 +1,185 @@
+#!/usr/bin/env sh
+
+#
+# Copyright 2015 the original author or authors.
+#
+# 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
+#
+#      https://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.
+#
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"'
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn () {
+    echo "$*"
+}
+
+die () {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+
+# Determine the Java command to use to start the JVM.
+if [ -n "$JAVA_HOME" ] ; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then
+        # IBM's JDK on AIX uses strange locations for the executables
+        JAVACMD="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin or MSYS, switch paths to Windows format before running java
+if [ "$cygwin" = "true" -o "$msys" = "true" ] ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=`expr $i + 1`
+    done
+    case $i in
+        0) set -- ;;
+        1) set -- "$args0" ;;
+        2) set -- "$args0" "$args1" ;;
+        3) set -- "$args0" "$args1" "$args2" ;;
+        4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
+}
+APP_ARGS=`save "$@"`
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
+
+exec "$JAVACMD" "$@"

gradlew.bat

@@ -0,0 +1,89 @@
+@rem
+@rem Copyright 2015 the original author or authors.
+@rem
+@rem Licensed under the Apache License, Version 2.0 (the "License");
+@rem you may not use this file except in compliance with the License.
+@rem You may obtain a copy of the License at
+@rem
+@rem      https://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Resolve any "." and ".." in APP_HOME to make it shorter.
+for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m"
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto execute
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %*
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega

settings.gradle

@@ -0,0 +1,18 @@
+/*
+ * Copyright (C) 2020 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.
+ */
+
+rootProject.name = "StateCodelab"
+include ':finished', ':start'

start/.gitignore

@@ -0,0 +1 @@
+/build

start/build.gradle

@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2020 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.
+ */
+
+plugins {
+    id 'com.android.application'
+    id 'kotlin-android'
+}
+
+android {
+    compileSdkVersion 31
+
+    defaultConfig {
+        applicationId "com.example.statecodelab"
+        minSdkVersion 21
+        targetSdkVersion 31
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+        useIR = true
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    buildFeatures {
+        compose true
+        viewBinding true
+    }
+    composeOptions {
+        kotlinCompilerExtensionVersion "$compose_version"
+    }
+}
+
+dependencies {
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
+    implementation 'androidx.core:core-ktx:1.7.0'
+    implementation 'androidx.appcompat:appcompat:1.3.1'
+    implementation 'com.google.android.material:material:1.4.0'
+    implementation "androidx.fragment:fragment-ktx:1.3.6"
+    implementation "androidx.activity:activity-compose:$activity_compose_version"
+    implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.4.0"
+    implementation "androidx.lifecycle:lifecycle-viewmodel-savedstate:2.4.0"
+    implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.4.0"
+    implementation "androidx.lifecycle:lifecycle-viewmodel-compose:$viewmodel_compose_version"
+
+    implementation "androidx.compose.animation:animation:$compose_version"
+    implementation "androidx.compose.foundation:foundation:$compose_version"
+    implementation "androidx.compose.foundation:foundation-layout:$compose_version"
+    implementation "androidx.compose.material:material:$compose_version"
+    implementation "androidx.compose.material:material-icons-extended:$compose_version"
+    implementation "androidx.compose.runtime:runtime-livedata:$compose_version"
+    implementation "androidx.compose.runtime:runtime:$compose_version"
+    implementation "androidx.compose.ui:ui:$compose_version"
+    implementation "androidx.compose.ui:ui-tooling-preview:$compose_version"
+    debugImplementation "androidx.compose.ui:ui-tooling:$compose_version"
+
+    testImplementation 'junit:junit:4.13.2'
+    testImplementation "com.google.truth:truth:1.1.2"
+
+    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
+}
+
+// Compiler flag to use experimental Compose APIs
+tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).configureEach {
+    kotlinOptions {
+        jvmTarget = "1.8"
+        freeCompilerArgs += [
+                "-Xopt-in=kotlin.RequiresOptIn"
+        ]
+    }
+}

start/src/main/AndroidManifest.xml

@@ -0,0 +1,47 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 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.codelabs.state">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:supportsRtl="true"
+        android:exported="true"
+        android:theme="@style/Theme.StateCodelab">
+        <activity
+            android:name="com.codelabs.state.todo.TodoActivity"
+            android:label="@string/app_name"
+            android:exported="true"
+            android:theme="@style/Theme.StateCodelab.NoActionBar">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+        <activity android:name="com.codelabs.state.examples.HelloCodelabActivity"
+            android:exported="true"
+            />
+        <activity android:name="com.codelabs.state.examples.HelloCodeLabActivityWithViewModel"
+            android:exported="true"
+            />
+    </application>
+
+</manifest>

start/src/main/java/com/codelabs/state/examples/HelloCodelabActivity.kt

@@ -0,0 +1,150 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.examples
+
+import android.os.Bundle
+import androidx.activity.compose.setContent
+import androidx.activity.viewModels
+import androidx.appcompat.app.AppCompatActivity
+import androidx.compose.foundation.layout.Column
+import androidx.compose.material.Text
+import androidx.compose.material.TextField
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.livedata.observeAsState
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.core.widget.doAfterTextChanged
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewmodel.compose.viewModel
+import com.codelabs.state.databinding.ActivityHelloCodelabBinding
+
+/**
+ * An example showing unstructured state stored in an Activity.
+ */
+class HelloCodelabActivity : AppCompatActivity() {
+
+    private lateinit var binding: ActivityHelloCodelabBinding
+    var name = ""
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        binding = ActivityHelloCodelabBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        // doAfterTextChange is an event that modifies state
+        binding.textInput.doAfterTextChanged { text ->
+            name = text.toString()
+            updateHello()
+        }
+    }
+
+    /**
+     * This function updates the screen to show the current state of [name]
+     */
+    private fun updateHello() {
+        binding.helloText.text = "Hello, $name"
+    }
+}
+
+/**
+ * A ViewModel extracts _state_ from the UI and defines _events_ that can update it.
+ */
+class HelloViewModel : ViewModel() {
+
+    // LiveData holds state which is observed by the UI
+    // (state flows down from ViewModel)
+    private val _name = MutableLiveData("")
+    val name: LiveData<String> = _name
+
+    // onNameChanged is an event we're defining that the UI can invoke
+    // (events flow up from UI)
+    fun onNameChanged(newName: String) {
+        _name.value = newName
+    }
+}
+
+/**
+ * An example showing unidirectional data flow in the View system using a ViewModel.
+ */
+class HelloCodeLabActivityWithViewModel : AppCompatActivity() {
+    private val helloViewModel by viewModels<HelloViewModel>()
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        val binding = ActivityHelloCodelabBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        // doAfterTextChange is an event that triggers an event on the ViewModel
+        binding.textInput.doAfterTextChanged {
+            // onNameChanged is an event on the ViewModel
+            helloViewModel.onNameChanged(it.toString())
+        }
+        // [helloViewModel.name] is state that we observe to update the UI
+        helloViewModel.name.observe(this) { name ->
+            binding.helloText.text = "Hello, $name"
+        }
+    }
+}
+
+class HelloActivityCompose : AppCompatActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContent {
+            HelloScreen()
+        }
+    }
+}
+
+@Composable
+private fun HelloScreen(helloViewModel: HelloViewModel = viewModel()) {
+    // helloViewModel follows the Lifecycle as the the Activity or Fragment that calls this
+    // composable function.
+
+    // name is the _current_ value of [helloViewModel.name]
+    val name: String by helloViewModel.name.observeAsState("")
+
+    HelloInput(name = name, onNameChange = { helloViewModel.onNameChanged(it) })
+}
+
+@Composable
+private fun HelloScreenWithInternalState() {
+    val (name, setName) = remember { mutableStateOf("") }
+    HelloInput(name = name, onNameChange = setName)
+}
+
+/**
+ * @param name (state) current text to display
+ * @param onNameChange (event) request that text change
+ */
+@Composable
+private fun HelloInput(
+    name: String,
+    onNameChange: (String) -> Unit
+) {
+    Column {
+        Text(name)
+        TextField(
+            value = name,
+            onValueChange = onNameChange,
+            label = { Text("Name") }
+        )
+    }
+}

start/src/main/java/com/codelabs/state/test/test.kt

@@ -0,0 +1,17 @@
+package com.codelabs.state.test
+
+fun main(args:Array<String>) {
+    test2()
+}
+
+fun test1(){
+    val a:String? = null
+    val b = requireNotNull(a)
+
+}
+
+fun test2(){
+    require(1==1){
+        "You can only change an item with the same id as currentEditItem"
+    }
+}

start/src/main/java/com/codelabs/state/todo/Data.kt

@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.todo
+
+import androidx.annotation.StringRes
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.CropSquare
+import androidx.compose.material.icons.filled.Done
+import androidx.compose.material.icons.filled.Event
+import androidx.compose.material.icons.filled.PrivacyTip
+import androidx.compose.material.icons.filled.RestoreFromTrash
+import androidx.compose.ui.graphics.vector.ImageVector
+import com.codelabs.state.R
+import java.util.UUID
+
+data class TodoItem(
+    val task: String,
+    val icon: TodoIcon = TodoIcon.Default,
+    // since the user may generate identical tasks, give them each a unique ID
+    val id: UUID = UUID.randomUUID()
+)
+
+enum class TodoIcon(val imageVector: ImageVector, @StringRes val contentDescription: Int) {
+    Square(Icons.Default.CropSquare, R.string.cd_expand),
+    Done(Icons.Default.Done, R.string.cd_done),
+    Event(Icons.Default.Event, R.string.cd_event),
+    Privacy(Icons.Default.PrivacyTip, R.string.cd_privacy),
+    Trash(Icons.Default.RestoreFromTrash, R.string.cd_restore);
+
+    companion object {
+        val Default = Square
+    }
+}

start/src/main/java/com/codelabs/state/todo/TodoActivity.kt

@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.todo
+
+import android.os.Bundle
+import androidx.activity.compose.setContent
+import androidx.activity.viewModels
+import androidx.appcompat.app.AppCompatActivity
+import androidx.compose.foundation.layout.Column
+import androidx.compose.material.Button
+import androidx.compose.material.Surface
+import androidx.compose.material.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import com.codelabs.state.test.test1
+import com.codelabs.state.test.test2
+import com.codelabs.state.ui.StateCodelabTheme
+
+class TodoActivity : AppCompatActivity() {
+
+    val todoViewModel by viewModels<TodoViewModel>()
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContent {
+            StateCodelabTheme {
+                Surface {
+                    BodyContent(todoViewModel)
+                }
+            }
+        }
+    }
+
+
+}
+
+@Composable
+fun BodyContent1(todoViewModel: TodoViewModel){
+    /*val (text,setText) = remember {
+        mutableStateOf("")
+    }*/
+    val text =  remember {
+        mutableStateOf("")
+    }
+    Column {
+        TodoInputText(text = text.value, onTextChange = text.component2())
+        Text(text.value)
+
+        Button(onClick = { test1()}) {
+            Text(text = "test1")
+        }
+
+        Button(onClick = { test2() }) {
+            Text(text = "test2")
+        }
+    }
+}
+
+@Composable
+fun BodyContent(viewModel: TodoViewModel){
+//    val list = todoViewModel.todoItems.observeAsState(listOf())
+    //val list = todoViewModel.todoItems.collectAsState()
+    TodoScreen(
+        items = viewModel.todoItems,
+        onAddItem = viewModel::addItem,
+        onRemoveItem = viewModel::removeItem,
+        onEditItemChange = viewModel::onEditItemChange,
+        onEditDone = viewModel::onEditDone,
+        onEditItemSelected = viewModel::onEditItemSelected,
+        currentlyEditing = viewModel.currentEditItem
+    )
+}

start/src/main/java/com/codelabs/state/todo/TodoComponents.kt

@@ -0,0 +1,300 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.todo
+
+import androidx.annotation.StringRes
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.ExperimentalAnimationApi
+import androidx.compose.animation.animateContentSize
+import androidx.compose.animation.core.*
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.RowScope
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.defaultMinSize
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.foundation.text.KeyboardActions
+import androidx.compose.foundation.text.KeyboardOptions
+import androidx.compose.material.Icon
+import androidx.compose.material.MaterialTheme
+import androidx.compose.material.Surface
+import androidx.compose.material.Text
+import androidx.compose.material.TextButton
+import androidx.compose.material.TextField
+import androidx.compose.material.TextFieldDefaults
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.remember
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.RectangleShape
+import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.platform.LocalSoftwareKeyboardController
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.input.ImeAction
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+
+/**
+ * Draws a row of [TodoIcon] with visibility changes animated.
+ *
+ * When not visible, will collapse to 16.dp high by default. You can enlarge this with the passed
+ * modifier.
+ *
+ * @param icon (state) the current selected icon
+ * @param onIconChange (event) request the selected icon change
+ * @param modifier modifier for this element
+ * @param visible (state) if the icon should be shown
+ */
+@OptIn(ExperimentalAnimationApi::class)
+@Composable
+fun AnimatedIconRow1(
+    icon: TodoIcon,
+    onIconChange: (TodoIcon) -> Unit,
+    modifier: Modifier = Modifier,
+    visibleState :MutableTransitionState<Boolean>
+) {
+    // remember these specs so they don't restart if recomposing during the animation
+    // this is required since TweenSpec restarts on interruption
+    val enter = remember { fadeIn(animationSpec = TweenSpec(200, easing = FastOutLinearInEasing)) }
+    val exit = remember { fadeOut(animationSpec = TweenSpec(100, easing = FastOutSlowInEasing)) }
+    Box(modifier.defaultMinSize(minHeight = 16.dp)) {
+        AnimatedVisibility(
+            visibleState,
+            enter = enter,
+            exit = exit,
+        ) {
+            IconRow(icon, onIconChange)
+
+        }
+    }
+}
+
+@Composable
+fun AnimatedIconRow(
+    icon: TodoIcon,
+    onIconChange: (TodoIcon) -> Unit,
+    modifier: Modifier = Modifier,
+    visible:Boolean
+) {
+    // remember these specs so they don't restart if recomposing during the animation
+    // this is required since TweenSpec restarts on interruption
+    val enter = remember { fadeIn(animationSpec = TweenSpec(200, easing = FastOutLinearInEasing)) }
+    val exit = remember { fadeOut(animationSpec = TweenSpec(100, easing = FastOutSlowInEasing)) }
+    Box(modifier.defaultMinSize(minHeight = 16.dp)) {
+        AnimatedVisibility(
+            visible,
+            enter = enter,
+            exit = exit,
+        ) {
+            IconRow(icon, onIconChange)
+
+        }
+    }
+}
+
+/**
+ * Displays a row of selectable [TodoIcon]
+ *
+ * @param icon (state) the current selected icon
+ * @param onIconChange (event) request the selected icon change
+ * @param modifier modifier for this element
+ */
+@Composable
+fun IconRow(
+    icon: TodoIcon,
+    onIconChange: (TodoIcon) -> Unit,
+    modifier: Modifier = Modifier
+) {
+    Row(modifier) {
+        for (todoIcon in TodoIcon.values()) {
+            SelectableIconButton(
+                icon = todoIcon.imageVector,
+                iconContentDescription = todoIcon.contentDescription,
+                onIconSelected = { onIconChange(todoIcon) },
+                isSelected = todoIcon == icon
+            )
+        }
+    }
+}
+
+/**
+ * Displays a single icon that can be selected.
+ *
+ * @param icon the icon to draw
+ * @param onIconSelected (event) request this icon be selected
+ * @param isSelected (state) selection state
+ * @param modifier modifier for this element
+ */
+@Composable
+private fun SelectableIconButton(
+    icon: ImageVector,
+    @StringRes iconContentDescription: Int,
+    onIconSelected: () -> Unit,
+    isSelected: Boolean,
+    modifier: Modifier = Modifier
+) {
+    val tint = if (isSelected) {
+        MaterialTheme.colors.primary
+    } else {
+        MaterialTheme.colors.onSurface.copy(alpha = 0.6f)
+    }
+    TextButton(
+        onClick = { onIconSelected() },
+        shape = CircleShape,
+        modifier = modifier
+    ) {
+        Column {
+            Icon(
+                imageVector = icon,
+                tint = tint,
+                contentDescription = stringResource(id = iconContentDescription)
+            )
+            if (isSelected) {
+                Box(
+                    Modifier
+                        .padding(top = 3.dp)
+                        .width(icon.defaultWidth)
+                        .height(1.dp)
+                        .background(tint)
+                )
+            } else {
+                Spacer(modifier = Modifier.height(4.dp))
+            }
+        }
+    }
+}
+
+/**
+ * Draw a background based on [MaterialTheme.colors.onSurface] that animates resizing and elevation
+ * changes.
+ *
+ * @param elevate draw a shadow, changes to this will be animated
+ * @param modifier modifier for this element
+ * @param content (slot) content to draw in the background
+ */
+@Composable
+fun TodoItemInputBackground(
+    elevate: Boolean,
+    modifier: Modifier = Modifier,
+    content: @Composable RowScope.() -> Unit
+) {
+    val animatedElevation by animateDpAsState(if (elevate) 1.dp else 0.dp, TweenSpec(500))
+    Surface(
+        color = MaterialTheme.colors.onSurface.copy(alpha = 0.05f),
+        elevation = animatedElevation,
+        shape = RectangleShape,
+    ) {
+        Row(
+            modifier = modifier.animateContentSize(animationSpec = TweenSpec(300)),
+            content = content
+        )
+    }
+}
+
+/**
+ * Styled [TextField] for inputting a [TodoItem].
+ *
+ * @param text (state) current text to display
+ * @param onTextChange (event) request the text change state
+ * @param modifier the modifier for this element
+ * @param onImeAction (event) notify caller of [ImeAction.Done] events
+ */
+@OptIn(ExperimentalComposeUiApi::class)
+@Composable
+fun TodoInputText(
+    text: String,
+    onTextChange: (String) -> Unit,
+    modifier: Modifier = Modifier,
+    onImeAction: () -> Unit = {}
+) {
+    val keyboardController = LocalSoftwareKeyboardController.current
+    TextField(
+        value = text,
+        onValueChange = onTextChange,
+        colors = TextFieldDefaults.textFieldColors(backgroundColor = Color.Transparent),
+        maxLines = 1,
+        keyboardOptions = KeyboardOptions.Default.copy(imeAction = ImeAction.Done),
+        keyboardActions = KeyboardActions(onDone = {
+            onImeAction()
+            keyboardController?.hide()
+        }),
+        modifier = modifier
+    )
+}
+
+/**
+ * Styled button for [TodoScreen]
+ *
+ * @param onClick (event) notify caller of click events
+ * @param text button text
+ * @param modifier modifier for button
+ * @param enabled enable or disable the button
+ */
+@Composable
+fun TodoAddButton(
+    onClick: () -> Unit,
+    text: String,
+    modifier: Modifier = Modifier,
+    enabled: Boolean = true
+) {
+    TextButton(
+        onClick = onClick,
+        shape = CircleShape,
+        enabled = enabled,
+        modifier = modifier
+    ) {
+        Text(text)
+    }
+}
+
+/**
+ * Styled button for [TodoScreen]
+ *
+ * @param onClick (event) notify caller of click events
+ * @param text button text
+ * @param modifier modifier for button
+ * @param enabled enable or disable the button
+ */
+@Composable
+fun TodoEditButton(
+    onClick: () -> Unit,
+    text: String,
+    modifier: Modifier = Modifier,
+    enabled: Boolean = true
+) {
+    TextButton(
+        onClick = onClick,
+        shape = CircleShape,
+        enabled = enabled,
+        modifier = modifier
+    ) {
+        Text(text)
+    }
+}
+
+@Preview
+@Composable
+fun PreviewIconRow() = IconRow(icon = TodoIcon.Square, onIconChange = {})

start/src/main/java/com/codelabs/state/todo/TodoScreen.kt

@@ -0,0 +1,282 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.todo
+
+import android.widget.Space
+import androidx.compose.animation.core.MutableTransitionState
+import androidx.compose.foundation.clickable
+import androidx.compose.foundation.layout.*
+import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.lazy.items
+import androidx.compose.material.*
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Delete
+import androidx.compose.material.icons.filled.Save
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Alignment.Companion.CenterVertically
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import com.codelabs.state.util.generateRandomTodoItem
+import kotlin.random.Random
+
+/**
+ * Stateless component that is responsible for the entire todo screen.
+ *
+ * @param items (state) list of [TodoItem] to display
+ * @param onAddItem (event) request an item be added
+ * @param onRemoveItem (event) request an item be removed
+ */
+@Composable
+fun TodoScreen(
+    items: List<TodoItem>,
+    onAddItem: (TodoItem) -> Unit,
+    onRemoveItem: (TodoItem) -> Unit,
+    currentlyEditing: TodoItem?,
+    onEditItemChange: (TodoItem) -> Unit,
+    onEditDone: () -> Unit,
+    onEditItemSelected: (TodoItem) -> Unit,
+) {
+    Column {
+        // add TodoItemInputBackground and TodoItem at the top of TodoScreen
+        //TodoItemInputBackground(elevate = true, modifier = Modifier.fillMaxWidth()) {
+        TodoItemEntryInput(onItemComplete = onAddItem)
+        //}
+        LazyColumn(
+            modifier = Modifier.weight(1f),
+            contentPadding = PaddingValues(top = 8.dp)
+        ) {
+            items(items = items) {
+                if (it.id == currentlyEditing?.id) {
+                    TodoItemInlineEditor(
+                        item = currentlyEditing,
+                        onEditItemChange = onEditItemChange,
+                        onRemoveItem = onRemoveItem,
+                        onEditDone = onEditDone
+                    ){
+                        Row {
+                            IconButton(
+                                onClick = onEditDone,
+                                modifier = Modifier
+                                    .align(CenterVertically)
+                                    .padding(end = 8.dp),
+                                enabled = currentlyEditing.task.isNotBlank()
+                            ) {
+                                Icon(Icons.Default.Save, contentDescription = "save")
+                            }
+                            IconButton(
+                                onClick = { onRemoveItem(it) },
+                                modifier = Modifier.align(CenterVertically)
+                            ) {
+                                Icon(
+                                    Icons.Default.Delete,
+                                    contentDescription = "delete",
+                                    tint = Color.Red
+                                )
+                            }
+                        }
+                    }
+                } else {
+                    TodoRow(
+                        todo = it,
+                        onItemClicked = onEditItemSelected,
+                        modifier = Modifier.fillParentMaxWidth()
+                    )
+                }
+
+            }
+        }
+
+        // For quick testing, a random item generator button
+        Button(
+            onClick = { onAddItem(generateRandomTodoItem()) },
+            modifier = Modifier
+                .padding(16.dp)
+                .fillMaxWidth(),
+        ) {
+            Text("Add random item")
+        }
+    }
+}
+
+@Composable
+fun TodoItemEntryInput(onItemComplete: (TodoItem) -> Unit) {
+    // onItemComplete is an event will fire when an item is completed by the user
+    val (text, setText) = remember { mutableStateOf("") }
+    val (icon, setIcon) = remember { mutableStateOf(TodoIcon.Default) }
+    val iconsVisible = text.isNotBlank()
+    val submit = {
+        onItemComplete.invoke(TodoItem(text, icon))
+        setIcon(TodoIcon.Default)
+        setText("")
+    }
+    TodoItemInput(text, setText, submit, iconsVisible, icon, setIcon){
+        TodoEditButton(
+            onClick = submit,
+            text = "Add",
+            enabled = text.isNotBlank()
+        )
+    }
+}
+
+@Composable
+fun TodoItemInlineEditor(
+    item: TodoItem,
+    onEditItemChange: (TodoItem) -> Unit,
+    onRemoveItem: (TodoItem) -> Unit,
+    onEditDone: () -> Unit,
+    buttonSlot: @Composable BoxScope.() -> Unit,
+) = TodoItemInput(
+    text = item.task,
+    onTextChanged = { onEditItemChange(item.copy(task = it)) },
+    onIconChanged = { onEditItemChange(item.copy(icon = it)) },
+    icon = item.icon,
+    iconsVisible = true,
+    submit = onEditDone,
+    buttonSlot = buttonSlot
+)
+
+@Composable
+fun TodoItemInput(
+    text: String,
+    onTextChanged: (String) -> Unit,
+    submit: () -> Unit,
+    iconsVisible: Boolean,
+    icon: TodoIcon,
+    onIconChanged: (TodoIcon) -> Unit,
+    //onRemoveItem: (() -> Unit)? = null,
+    buttonSlot: @Composable BoxScope.() -> Unit,
+) {
+    Column {
+        Row(
+            Modifier
+                .padding(horizontal = 16.dp)
+                .padding(top = 16.dp)
+        ) {
+            TodoInputText(
+                text = text,
+                onTextChange = onTextChanged,
+                modifier = Modifier
+                    .weight(1f)
+                    .padding(end = 8.dp),
+                onImeAction = submit
+            )
+            Spacer(modifier = Modifier.width(8.dp))
+            Box(modifier = Modifier.align(CenterVertically)){
+                buttonSlot()
+            }
+            /*if (onRemoveItem != null) {
+                IconButton(
+                    onClick = submit,
+                    modifier = Modifier
+                        .align(Alignment.CenterVertically)
+                        .padding(end = 8.dp),
+                    enabled = text.isNotBlank()
+                ) {
+                    Icon(Icons.Default.Save, contentDescription = "save")
+                }
+                IconButton(
+                    onClick = onRemoveItem,
+                    modifier = Modifier.align(Alignment.CenterVertically)
+                ) {
+                    Icon(Icons.Default.Delete, contentDescription = "delete", tint = Color.Red)
+                }
+            } else {
+                TodoEditButton(
+                    onClick = submit,
+                    text = "Add",
+                    modifier = Modifier.align(Alignment.CenterVertically),
+                    enabled = text.isNotBlank()
+                )
+            }*/
+
+        }
+        /*val animVisibleState = remember { MutableTransitionState(!iconsVisible) }
+            .apply { targetState = iconsVisible }
+        if (!animVisibleState.currentState && !animVisibleState.targetState && !iconsVisible) {
+        }*/
+        if(iconsVisible){
+            AnimatedIconRow(icon, onIconChanged, Modifier.padding(top = 8.dp), iconsVisible)
+        }else{
+            Spacer(modifier = Modifier.height(8.dp))
+        }
+    }
+}
+
+@Composable
+fun TodoInputTextField(
+    text: String,
+    onTextChange: (String) -> Unit, modifier: Modifier
+) {
+
+    TodoInputText(text, onTextChange, modifier)
+}
+
+/**
+ * Stateless composable that displays a full-width [TodoItem].
+ *
+ * @param todo item to show
+ * @param onItemClicked (event) notify caller that the row was clicked
+ * @param modifier modifier for this element
+ */
+@Composable
+fun TodoRow(todo: TodoItem, onItemClicked: (TodoItem) -> Unit, modifier: Modifier = Modifier) {
+    Row(
+        modifier = modifier
+            .clickable { onItemClicked(todo) }
+            .padding(horizontal = 16.dp, vertical = 8.dp),
+        horizontalArrangement = Arrangement.SpaceBetween
+    ) {
+        Text(todo.task)
+        /*val alpha = remember(todo.id) {
+            randomTint()
+        }*/
+        Icon(
+            imageVector = todo.icon.imageVector,
+//            tint = LocalContentColor.current.copy(alpha = alpha),
+            contentDescription = stringResource(id = todo.icon.contentDescription)
+        )
+    }
+}
+
+private fun randomTint(): Float {
+    return Random.nextFloat().coerceIn(0.3f, 0.9f)
+}
+
+@Preview
+@Composable
+fun PreviewTodoScreen() {
+    /*val items = listOf(
+        TodoItem("Learn compose", TodoIcon.Event),
+        TodoItem("Take the codelab"),
+        TodoItem("Apply state", TodoIcon.Done),
+        TodoItem("Build dynamic UIs", TodoIcon.Square)
+    )
+    TodoScreen(items, {}, {},{},{})*/
+}
+
+@Preview
+@Composable
+fun PreviewTodoRow() {
+    val todo = remember { generateRandomTodoItem() }
+    TodoRow(todo = todo, onItemClicked = {}, modifier = Modifier.fillMaxWidth())
+}

start/src/main/java/com/codelabs/state/todo/TodoViewModel.kt

@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.todo
+
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateListOf
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshots.SnapshotStateList
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.ViewModel
+import kotlinx.coroutines.flow.MutableStateFlow
+
+class TodoViewModel : ViewModel() {
+
+//    private var _todoItems = MutableLiveData(listOf<TodoItem>())
+//    val todoItems: MutableStateFlow<SnapshotStateList<TodoItem>> = MutableStateFlow(mutableStateListOf())
+
+
+
+    /*fun addItem1(item: TodoItem) {
+        _todoItems.value = listOf(item)+_todoItems.value!!
+    }
+
+    fun removeItem1(item: TodoItem) {
+        _todoItems.value = _todoItems.value!!.toMutableList().also {
+            it.remove(item)
+        }
+    }*/
+
+    val todoItems = mutableStateListOf<TodoItem>()
+
+    // private state
+    private var currentEditPosition  =-1
+
+    // state
+    /*val currentEditItem: TodoItem?
+        get() = todoItems.getOrNull(currentEditPosition)*/
+    var currentEditItem: TodoItem? by mutableStateOf(null)
+
+    fun addItem(item: TodoItem) {
+        todoItems.add(item)
+    }
+
+    fun removeItem(item: TodoItem) {
+        todoItems.remove(item)
+        onEditDone()
+    }
+
+    // event: onEditItemSelected
+    fun onEditItemSelected(item: TodoItem) {
+        currentEditPosition = todoItems.indexOf(item)
+        currentEditItem = todoItems.getOrNull(currentEditPosition)
+    }
+
+    // event: onEditDone
+    fun onEditDone() {
+        currentEditItem?.let {
+            todoItems[currentEditPosition] = it
+        }
+        currentEditPosition = -1
+        currentEditItem = null
+    }
+
+    // event: onEditItemChange
+    fun onEditItemChange(item: TodoItem) {
+        val currentItem = requireNotNull(currentEditItem)
+        require(currentItem.id == item.id) {
+            "You can only change an item with the same id as currentEditItem"
+        }
+
+        currentEditItem = item
+    }
+}

start/src/main/java/com/codelabs/state/ui/Color.kt

@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.ui
+
+import androidx.compose.ui.graphics.Color
+
+val purple200 = Color(0xFFBB86FC)
+val purple500 = Color(0xFF6200EE)
+val purple700 = Color(0xFF3700B3)
+val teal200 = Color(0xFF03DAC5)

start/src/main/java/com/codelabs/state/ui/Shape.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.ui
+
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material.Shapes
+import androidx.compose.ui.unit.dp
+
+val shapes = Shapes(
+    small = RoundedCornerShape(4.dp),
+    medium = RoundedCornerShape(4.dp),
+    large = RoundedCornerShape(0.dp)
+)

start/src/main/java/com/codelabs/state/ui/Theme.kt

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.ui
+
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.material.MaterialTheme
+import androidx.compose.material.darkColors
+import androidx.compose.material.lightColors
+import androidx.compose.runtime.Composable
+
+private val DarkColorPalette = darkColors(
+    primary = purple200,
+    primaryVariant = purple700,
+    secondary = teal200
+)
+
+private val LightColorPalette = lightColors(
+    primary = purple500,
+    primaryVariant = purple700,
+    secondary = teal200
+)
+
+@Composable
+fun StateCodelabTheme(
+    darkTheme: Boolean = isSystemInDarkTheme(),
+    content: @Composable() () -> Unit
+) {
+    val colors = if (darkTheme) {
+        DarkColorPalette
+    } else {
+        LightColorPalette
+    }
+
+    MaterialTheme(
+        colors = colors,
+        typography = typography,
+        shapes = shapes,
+        content = content
+    )
+}

start/src/main/java/com/codelabs/state/ui/Type.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.ui
+
+import androidx.compose.material.Typography
+import androidx.compose.ui.text.TextStyle
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.sp
+
+// Set of Material typography styles to start with
+val typography = Typography(
+    body1 = TextStyle(
+        fontFamily = FontFamily.Default,
+        fontWeight = FontWeight.Normal,
+        fontSize = 16.sp
+    )
+)

start/src/main/java/com/codelabs/state/util/DataGenerators.kt

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.util
+
+import com.codelabs.state.todo.TodoIcon
+import com.codelabs.state.todo.TodoItem
+
+fun generateRandomTodoItem(): TodoItem {
+    val message = listOf(
+        "Learn compose",
+        "Learn state",
+        "Build dynamic UIs",
+        "Learn Unidirectional Data Flow",
+        "Integrate LiveData",
+        "Integrate ViewModel",
+        "Remember to savedState!",
+        "Build stateless composables",
+        "Use state from stateless composables"
+    ).random()
+    val icon = TodoIcon.values().random()
+    return TodoItem(message, icon)
+}
+
+fun main() {
+    val list = listOf(1, 2, 3)
+    var currentCount = 0
+    for (item in list) {
+        currentCount += item
+        println(currentCount)
+    }
+}

start/src/main/res/drawable/ic_launcher_background.xml

@@ -0,0 +1,186 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 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="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path
+        android:fillColor="#3DDC84"
+        android:pathData="M0,0h108v108h-108z" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M9,0L9,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,0L19,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,0L29,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,0L39,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,0L49,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,0L59,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,0L69,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,0L79,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M89,0L89,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M99,0L99,108"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,9L108,9"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,19L108,19"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,29L108,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,39L108,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,49L108,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,59L108,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,69L108,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,79L108,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,89L108,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M0,99L108,99"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,29L89,29"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,39L89,39"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,49L89,49"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,59L89,59"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,69L89,69"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M19,79L89,79"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M29,19L29,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M39,19L39,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M49,19L49,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M59,19L59,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M69,19L69,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+    <path
+        android:fillColor="#00000000"
+        android:pathData="M79,19L79,89"
+        android:strokeWidth="0.8"
+        android:strokeColor="#33FFFFFF" />
+</vector>

start/src/main/res/layout/activity_hello_codelab.xml

@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 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.
+  -->
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:orientation="vertical" android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:layout_margin="16dp">
+
+    <Space
+        android:layout_width="match_parent"
+        android:layout_height="100dp" />
+    <TextView
+        android:id="@+id/hello_text"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:gravity="center_horizontal"
+        android:layout_marginBottom="16dp"
+        android:textAppearance="?textAppearanceHeadline6" />
+
+    <EditText
+        android:id="@+id/text_input"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        />
+</LinearLayout>

start/src/main/res/values-night/themes.xml

@@ -0,0 +1,32 @@
+<!--
+  ~ Copyright (C) 2020 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="Theme.StateCodelab" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
+        <!-- Primary brand color. -->
+        <item name="colorPrimary">@color/purple_200</item>
+        <item name="colorPrimaryVariant">@color/purple_700</item>
+        <item name="colorOnPrimary">@color/black</item>
+        <!-- Secondary brand color. -->
+        <item name="colorSecondary">@color/teal_200</item>
+        <item name="colorSecondaryVariant">@color/teal_200</item>
+        <item name="colorOnSecondary">@color/black</item>
+        <!-- Status bar color. -->
+        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>
+        <!-- Customize your theme here. -->
+    </style>
+</resources>

start/src/main/res/values/colors.xml

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 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="purple_200">#FFBB86FC</color>
+    <color name="purple_500">#FF6200EE</color>
+    <color name="purple_700">#FF3700B3</color>
+    <color name="teal_200">#FF03DAC5</color>
+    <color name="teal_700">#FF018786</color>
+    <color name="black">#FF000000</color>
+    <color name="white">#FFFFFFFF</color>
+</resources>

start/src/main/res/values/strings.xml

@@ -0,0 +1,26 @@
+<!--
+  ~ Copyright (C) 2020 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">StateCodelab</string>
+    <string name="cd_expand">Expand</string>
+    <string name="cd_collapse">Collapse</string>
+    <string name="cd_crop_square">Crop</string>
+    <string name="cd_done">Done</string>
+    <string name="cd_event">Event</string>
+    <string name="cd_privacy">Privacy</string>
+    <string name="cd_restore">Restore</string>
+</resources>

start/src/main/res/values/themes.xml

@@ -0,0 +1,37 @@
+<!--
+  ~ Copyright (C) 2020 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="Theme.StateCodelab" parent="Theme.MaterialComponents.DayNight.DarkActionBar">
+        <!-- Primary brand color. -->
+        <item name="colorPrimary">@color/purple_500</item>
+        <item name="colorPrimaryVariant">@color/purple_700</item>
+        <item name="colorOnPrimary">@color/white</item>
+        <!-- Secondary brand color. -->
+        <item name="colorSecondary">@color/teal_200</item>
+        <item name="colorSecondaryVariant">@color/teal_700</item>
+        <item name="colorOnSecondary">@color/black</item>
+        <!-- Status bar color. -->
+        <item name="android:statusBarColor" tools:targetApi="l">?attr/colorPrimaryVariant</item>
+        <!-- Customize your theme here. -->
+    </style>
+
+    <style name="Theme.StateCodelab.NoActionBar">
+        <item name="windowActionBar">false</item>
+        <item name="windowNoTitle">true</item>
+    </style>
+</resources>

start/src/test/java/com/codelabs/state/todo/TodoViewModelTest.kt

@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2020 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.codelabs.state.todo
+
+class TodoViewModelTest {
+    // TODO: Write tests
+}