Can't import androidx.datastore.dataStore (trying to recreate Google Codelab Example) - kotlin

Question

Problem:
I'm trying to recreate this codelab tutorial project https://developer.android.com/codelabs/android-proto-datastore, but Android Studio can't import androidx.datastore.dataStore
Steps:
create new Kotlin project with an empty Acivity
modify gradle file
Switch to Android Studio's Project view
create a folder named proto inside of app/src/main
create and modify file user_prefs.proto inside of app/src/main/proto
Build -> Clean Project -> rebuild project
Create a serializer class called UserPreferencesSerializer
Trying to add the following Code to the empty MainActivity.kt
private const val DATA_STORE_FILE_NAME = "user_prefs.pb"
private val Context.userPreferencesStore: DataStore
by dataStore(
fileName = DATA_STORE_FILE_NAME,
serializer = UserPreferencesSerializer )
After this step Android Studio marks dataStore and shows the warning "Unresolved reference: dataStore" I'm also unable to import androidx.datastore.dataStore, but I can't find a missing import in my gradle file. Please, can someone tell me how I can resolve this problem?
Code:
build.gradle
plugins {
id 'com.android.application'
id 'kotlin-android'
id "com.google.protobuf" version "0.8.12"
}
android {
compileSdkVersion 30
buildToolsVersion "30.0.2"
defaultConfig {
applicationId "com.example.test"
minSdkVersion 28
targetSdkVersion 30
versionCode 1
versionName "1.0"
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}
}
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}
kotlinOptions {
jvmTarget = '1.8'
}
}
dependencies {
implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
implementation 'androidx.core:core-ktx:1.3.2'
implementation 'androidx.appcompat:appcompat:1.2.0'
implementation 'com.google.android.material:material:1.3.0'
implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
testImplementation 'junit:junit:4.+'
androidTestImplementation 'androidx.test.ext:junit:1.1.2'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
implementation "androidx.datastore:datastore-core:1.0.0-alpha08"
implementation "com.google.protobuf:protobuf-javalite:3.11.0"
}
protobuf {
protoc {
artifact = "com.google.protobuf:protoc:3.10.0"
}
// Generates the java Protobuf-lite code for the Protobufs in this project. See
// https://github.com/google/protobuf-gradle-plugin#customizing-protobuf-compilation
// for more information.
generateProtoTasks {
all().each { task ->
task.builtins {
java {
option 'lite'
}
}
}
}
}
user_prefs.proto
syntax = "proto3";
option java_package = "com.example.test";
option java_multiple_files = true;
message UserPreferences {
// filter for showing / hiding completed tasks
bool show_completed = 1;
}
UserPreferencesSerializer
package com.example.test
import androidx.datastore.core.CorruptionException
import androidx.datastore.core.Serializer
import com.google.protobuf.InvalidProtocolBufferException
import java.io.InputStream
import java.io.OutputStream
object UserPreferencesSerializer : Serializer<UserPreferences> {
override val defaultValue: UserPreferences = UserPreferences.getDefaultInstance()
override suspend fun readFrom(input: InputStream): UserPreferences {
try {
return UserPreferences.parseFrom(input)
} catch (exception: InvalidProtocolBufferException) {
throw CorruptionException("Cannot read proto.", exception)
}
}
override suspend fun writeTo(t: UserPreferences, output: OutputStream) = t.writeTo(output)
}
MainActivity.kt
import android.content.Context
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.datastore.core.DataStore
private const val DATA_STORE_FILE_NAME = "user_prefs.pb"
private val Context.userPreferencesStore: DataStore<UserPreferences> by dataStore(
fileName = DATA_STORE_FILE_NAME,
serializer = UserPreferencesSerializer
)
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
}

Answer 1

I also had this problem while working on a project.
I found that I was using datastore-core and needed datastore-preferences. So I changed my dependency declaration from:
implementation 'androidx.datastore:datastore-core:1.0.0-alpha08'
to:
implementation 'androidx.datastore:datastore-preferences:1.0.0'
Possibly there was a breaking change between alpha08 and the 1.0.0 release.

Answer 2

The dataStore delegate is part of the androidx.datastore:datastore library.
Add the dependency to your modudle's build.gradle file. Replace $dataStoreVersion with the version of data store which you use, e.g. 1.0.0:
implementation "androidx.datastore:datastore:$dataStoreVersion"
You can find the available versions here in Google's Maven repository.
After adding this dependency, you can use by dataStore by adding the following import to your class:
import androidx.datastore.dataStore

Answer 3

In Android documentation:
val Context.dataStore: DataStore<Preferences> by preferencesDataStore(name = "settings")
This line should be at the top of your code.
See DataStore documenation

Answer 4

After a lot of searching, The problem is simple. Make sure Gradle is not in offline mode.
Also, ensure that you use this dependency.
implementation "androidx.datastore:datastore-preferences:$dataStoreVersion"