DataStore Preferences

DataStore Preferences is a persistent key-value data storage solution offered by Android Jetpack. It provides a lightweight and asynchronous approach to storing and retrieving small amounts of structured data within your Android applications.

Usage

Dependencies

Within your app module’s build.gradle.kts file, incorporate the following dependencies:

implementation(project(":datastore"))

Example

We provide you with DataStorePreferences class that serves as a foundation for building your custom DataStorepreferences . You can extend this class to create specific preferences for your app.

class ExamplePreferences(context: Context): DataStorePreferences(context, "example_preferences") {
  val testValueOrNull = getOrNull(PreferencesKeys.testKey)
  val testValueOrDefault = getOrDefault(PreferencesKeys.testKey, "default")
 
  suspend fun setTestValue(value: String) {
    set(PreferencesKeys.testKey, value)
  }
 
  private object PreferencesKeys {
    val testKey = stringPreferencesKey("test_key")
  }
}

The DataStorePreferences constructor accepts a name parameter, allowing you to customize the name of the preferences file. It also requires the context parameter to be able to create a DataStore File.

Furthermore it provides a few helper methods to store and retrieve data from the DataStore file.

• set(key: Preferences.Key<T>, value: T): This method allows you to store a value in the DataStore file for the given key.
• getOrNull(key: Preferences.Key<T>): Flow<T?>: This method allows you to retrieve a value from the DataStore file for the given key. It returns a Flow of the value so you can observe changes in the value. If the value is not found it returns null.
• getOrDefault(key: Preferences.Key<T>, defaultValue: T): Flow<T>: This method allows you to retrieve a value from the DataStore file for the given key. It returns a Flow of the value so you can observe changes in the value. If the value is not found it returns the default value provided.