androidx.datastore.preferences.core

booleanPreferencesKey

@JvmName("booleanKey") fun booleanPreferencesKey(name: String): Preferences.Key<Boolean>

Get a key for a Boolean preference. You should not have multiple keys with the same name (for use with the same Preferences). Using overlapping keys with different types can result in ClassCastException.

doublePreferencesKey

@JvmName("doubleKey") fun doublePreferencesKey(name: String): Preferences.Key<Double>

Get a key for a Double preference. You should not have multiple keys with the same name (for use with the same Preferences). Using overlapping keys with different types can result in ClassCastException.

emptyPreferences

@JvmName("createEmpty") fun emptyPreferences(): Preferences

Get a new empty Preferences.

floatPreferencesKey

@JvmName("floatKey") fun floatPreferencesKey(name: String): Preferences.Key<Float>

Get a key for a Float preference. You should not have multiple keys with the same name (for use with the same Preferences). Using overlapping keys with different types can result in ClassCastException.

intPreferencesKey

@JvmName("intKey") fun intPreferencesKey(name: String): Preferences.Key<Int>

Get a key for an Int preference. You should not have multiple keys with the same name (for use with the same Preferences). Using overlapping keys with different types can result in ClassCastException.

longPreferencesKey

@JvmName("longKey") fun longPreferencesKey(name: String): Preferences.Key<Long>

Get a key for an Long preference. You should not have multiple keys with the same name (for use with the same Preferences). Using overlapping keys with different types can result in ClassCastException.

mutablePreferencesOf

@JvmName("createMutable") fun mutablePreferencesOf(vararg pairs: Preferences.Pair<*>): MutablePreferences

Construct a MutablePreferences object with a list of Preferences.Pair. Comparable to mapOf().

Example usage:

val counterKey = intPreferencesKey("counter") val preferences = preferencesOf(counterKey to 100)

preferencesOf

@JvmName("create") fun preferencesOf(vararg pairs: Preferences.Pair<*>): Preferences

Construct a Preferences object with a list of Preferences.Pair. Comparable to mapOf().

Example usage:

val counterKey = intPreferencesKey("counter") val preferences = preferencesOf(counterKey to 100)

stringPreferencesKey

@JvmName("stringKey") fun stringPreferencesKey(name: String): Preferences.Key<String>

Get a key for a String preference. You should not have multiple keys with the same name (for use with the same Preferences). Using overlapping keys with different types can result in ClassCastException.

stringSetPreferencesKey

@JvmName("stringSetKey") fun stringSetPreferencesKey(name: String): Preferences.Key<Set<String>>

Get a key for a String Set preference. You should not have multiple keys with the same name (for use with the same Preferences). Using overlapping keys with different types can result in ClassCastException.

Note: sets returned by DataStore are unmodifiable and will throw exceptions if mutated.

edit

suspend fun DataStore<Preferences>.edit(transform: suspend (MutablePreferences) -> Unit): Preferences

Edit the value in DataStore transactionally in an atomic read-modify-write operation. All operations are serialized.

The coroutine completes when the data has been persisted durably to disk (after which DataStore.data will reflect the update). If the transform or write to disk fails, the transaction is aborted and an exception is thrown.

Note: values that are changed in transform are NOT updated in DataStore until after the transform completes. Do not assume that the data has been successfully persisted until after edit returns successfully.

Note: do NOT store a reference to the MutablePreferences provided to transform. Mutating this after transform returns will NOT change the data in DataStore. Future versions of this may throw exceptions if the MutablePreferences object is mutated outside of transform.

See DataStore.updateData.

Example usage: val COUNTER_KEY = intPreferencesKey("my_counter")

dataStore.edit { prefs -> prefs\[COUNTER_KEY\] = prefs\[COUNTER_KEY\] :? 0 + 1 }