MutablePreferences

Kotlin |Java

class MutablePreferences : Preferences

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

Mutable version of Preferences. Allows for creating Preferences with different key-value pairs.

Summary

Public methods
Map<Preferences.Key<*>, Any>	asMap() Retrieve a map of all key preference pairs.
Unit	clear()
operator Boolean	contains(key: Preferences.Key<T>) Returns true if this Preferences contains the specified key.
Boolean	equals(other: Any?)
operator T?	get(key: Preferences.Key<T>) Get a preference with a key.
Int	hashCode()
operator Unit	minusAssign(key: Preferences.Key<*>) Removes the preference with the given key from this MutablePreferences.
operator Unit	plusAssign(prefs: Preferences) Appends or replaces all pairs from prefs to this MutablePreferences.
operator Unit	plusAssign(pair: Preferences.Pair<*>) Appends or replaces all pair to this MutablePreferences.
Unit	putAll(vararg pairs: Preferences.Pair<*>) Appends or replaces all pairs to this MutablePreferences.
T	remove(key: Preferences.Key<T>) Remove a preferences from this MutablePreferences.
operator Unit	set(key: Preferences.Key<T>, value: T) Set a key value pair in MutablePreferences.
String	toString() For better debugging.

Inherited functions

From class Preferences MutablePreferences toMutablePreferences() 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. Preferences toPreferences() Gets a read-only copy of Preferences which contains all the preferences in this Preferences. This is similar to Map.toMap.

Public methods

asMap

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

clear

fun clear(): Unit

contains

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

equals

fun equals(other: Any?): Boolean

get

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

hashCode

fun hashCode(): Int

minusAssign

operator fun minusAssign(key: Preferences.Key<*>): Unit

Removes the preference with the given key from this MutablePreferences. If this Preferences does not contain the key, this is a no-op.

Example usage: mutablePrefs -= COUNTER_KEY

Parameters
key: Preferences.Key<*>	the key to remove from this MutablePreferences

plusAssign

operator fun plusAssign(prefs: Preferences): Unit

Appends or replaces all pairs from prefs to this MutablePreferences. Keys in prefs will overwrite keys in this Preferences.

Example usage: mutablePrefs += preferencesOf(COUNTER_KEY to 100, NAME to "abcdef")

Parameters
prefs: Preferences	Preferences to append to this MutablePreferences

plusAssign

operator fun plusAssign(pair: Preferences.Pair<*>): Unit

Appends or replaces all pair to this MutablePreferences.

Example usage: mutablePrefs += COUNTER_KEY to 100

Parameters
pair: Preferences.Pair<*>	the Preference.Pair to add to this MutablePreferences

putAll

fun putAll(vararg pairs: Preferences.Pair<*>): Unit

Appends or replaces all pairs to this MutablePreferences.

Parameters
vararg pairs: Preferences.Pair<*>	the pairs to append to this MutablePreferences

remove

fun <T> remove(key: Preferences.Key<T>): T

Remove a preferences from this MutablePreferences.

Parameters
key: Preferences.Key<T>	the key to remove this MutablePreferences

Return
the original value of this preference key.

set

operator fun <T> set(
    key: Preferences.Key<T>, 
    value: T
): Unit

Set a key value pair in MutablePreferences.

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

// Once edit completes successfully, preferenceStore will contain the incremented counter. preferenceStore.edit { prefs: MutablePreferences -> prefs\[COUNTER_KEY\] = prefs\[COUNTER_KEY\] :? 0 + 1 }

Parameters
key: Preferences.Key<T>	the preference to set
key: Preferences.Key<T>	the value to set the preference to

toString

fun toString(): String

For better debugging.