Preferences

Kotlin |Java

abstract class Preferences

kotlin.Any
↳	androidx.datastore.preferences.core.Preferences

Known Direct Subclasses MutablePreferences MutablePreferences Mutable version of Preferences.

Preferences and MutablePreferences are a lot like a generic Map and MutableMap keyed by the Preferences.Key class. These are intended for use with DataStore. Construct a DataStore instance using PreferenceDataStoreFactory.create.

Summary

Nested classes
	Key Key for values stored in Preferences.
	Pair Key Value pairs for Preferences.

Public methods
abstract Map<Preferences.Key<*>, Any>	asMap() Retrieve a map of all key preference pairs.
abstract operator Boolean	contains(key: Preferences.Key<T>) Returns true if this Preferences contains the specified key.
abstract operator T?	get(key: Preferences.Key<T>) Get a preference with a key.
MutablePreferences	toMutablePreferences() Gets a mutable copy of Preferences which contains all the preferences in this Preferences.
Preferences	toPreferences() Gets a read-only copy of Preferences which contains all the preferences in this Preferences.

Public methods

asMap

abstract fun asMap(): Map<Preferences.Key<*>, Any>

Retrieve a map of all key preference pairs. The returned map is unmodifiable, and attempts to mutate it will throw runtime exceptions.

Return
a map containing all the preferences in this Preferences

contains

abstract operator fun <T> contains(key: Preferences.Key<T>): Boolean

Returns true if this Preferences contains the specified key.

Parameters
key: Preferences.Key<T>	the key to check for

get

abstract operator fun <T> get(key: Preferences.Key<T>): T?

Get a preference with a key. If the key is not set, returns null.

If T is Set, this returns an unmodifiable set which will throw a runtime exception when mutated. Do not try to mutate the returned set.

Use MutablePreferences.set to change the value of a preference (inside a DataStore.edit block).

Parameters
T	the type of the preference
key: Preferences.Key<T>	the key for the preference

Exceptions
ClassCastException	if there is something stored with the same name as key but it cannot be cast to T

toMutablePreferences

fun toMutablePreferences(): MutablePreferences

Gets a mutable copy of Preferences which contains all the preferences in this Preferences. This can be used to update your preferences without building a new Preferences object from scratch in DataStore.updateData.

This is similar to Map.toMutableMap.

Return
a MutablePreferences with all the preferences from this Preferences

toPreferences

fun toPreferences(): Preferences

Gets a read-only copy of Preferences which contains all the preferences in this Preferences.

This is similar to Map.toMap.

Return
a copy of this Preferences