android datastore-preferences: Property delegate must have a 'getValue(Context, KProperty<*>)' method
I'm writing a jetpack compose android app, I need to store some settings permanently.
I decided to use androidx.datastore:datastore-preferences:1.0.0
library, I have added this to my classpath.
According to the https://developer.android.com/topic/libraries/architecture/datastore descripton I have added this line of code to my kotline file at the top level:
val Context.prefsDataStore: DataStore by preferencesDataStore(name = "settings")
But I get a compile error:
e: ...SettingsViewModel.kt: (13, 50): Property delegate must have a 'getValue(Context, KProperty<*>)' method. None of the following functions is suitable:
public abstract operator fun getValue(thisRef: Context, property: KProperty<*>): DataStore<Preferences> defined in kotlin.properties.ReadOnlyProperty
How can I use the datastore-preferences?
My build.gradle file:
plugins {
id 'com.android.application'
id 'kotlin-android'
id 'kotlin-kapt'
}
apply plugin: 'dagger.hilt.android.plugin'
apply plugin: 'kotlinx-serialization'
android {
compileSdk 31
defaultConfig {
applicationId "hu.homedashboard.mobile"
minSdk 22
targetSdk 31
versionCode 1
versionName "1.0"
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
vectorDrawables {
useSupportLibrary true
}
}
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'
useIR = true
}
buildFeatures {
compose true
}
composeOptions {
kotlinCompilerExtensionVersion compose_version
kotlinCompilerVersion "$kotlinVersion"
}
packagingOptions {
resources {
excludes += '/META-INF/{AL2.0,LGPL2.1}'
}
}
}
dependencies {
implementation "androidx.activity:activity-compose:1.3.1"
implementation "androidx.appcompat:appcompat:1.3.1"
implementation "androidx.datastore:datastore-preferences:1.0.0"
implementation "androidx.compose.material:material:$compose_version"
implementation "androidx.compose.ui:ui-tooling-preview:$compose_version"
implementation "androidx.compose.ui:ui:$compose_version"
implementation "com.google.accompanist:accompanist-swiperefresh:0.20.3"
implementation "androidx.core:core-ktx:1.6.0"
implementation "androidx.lifecycle:lifecycle-livedata-ktx:$lifecycle_version"
implementation "androidx.lifecycle:lifecycle-runtime-ktx:$lifecycle_version"
implementation "androidx.lifecycle:lifecycle-runtime-ktx:2.3.1"
implementation "androidx.lifecycle:lifecycle-viewmodel-compose:$lifecycle_version"
implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:$lifecycle_version"
implementation "androidx.navigation:navigation-compose:2.4.0-alpha10"
implementation "com.google.android.material:material:1.4.0"
implementation "com.google.dagger:hilt-android:2.40.1"
implementation "com.jakewharton.retrofit:retrofit2-kotlinx-serialization-converter:0.8.0"
implementation "com.squareup.retrofit2:retrofit:2.9.0"
implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion"
implementation "org.jetbrains.kotlinx:kotlinx-serialization-json:1.3.0"
implementation "org.ocpsoft.prettytime:prettytime:5.0.2.Final"
implementation 'androidx.hilt:hilt-navigation-compose:1.0.0-alpha03'
kapt "com.google.dagger:hilt-compiler:2.38.1"
kapt "com.google.dagger:dagger-android-processor:2.40.1"
kapt "com.google.guava:guava:31.0.1-android"
api "com.google.guava:guava:31.0.1-android"
testImplementation 'junit:junit:4.+'
androidTestImplementation 'androidx.test.ext:junit:1.1.3'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
androidTestImplementation "androidx.compose.ui:ui-test-junit4:$compose_version"
debugImplementation "androidx.compose.ui:ui-tooling:$compose_version"
}
kapt {
correctErrorTypes true
javacOptions {
option("-Xmaxerrs", 500)
}
}
I got this error because of an incorrect import:
import java.util.prefs.Preferences
So fix it by
import androidx.datastore.preferences.core.Preferences
or
val Context.dataStore by preferencesDataStore(name = "settings")