Added in API level 1

SharedPreferences

public interface SharedPreferences

android.content.SharedPreferences

Interface for accessing and modifying preference data returned by Context.getSharedPreferences(String, int). For any particular set of preferences, there is a single instance of this class that all clients share. Modifications to the preferences must go through an Editor object to ensure the preference values remain in a consistent state and control when they are committed to storage. Objects that are returned from the various get methods must be treated as immutable by the application.

SharedPreferences is best suited to storing data about how the user prefers to experience the app, for example, whether the user prefers a particular UI theme or whether they prefer viewing particular content in a list vs. a grid. To this end, SharedPreferences reflects changes committed or applied by Editors immediately, potentially before those changes are durably persisted. Under some circumstances such as app crashes or termination these changes may be lost, even if an OnSharedPreferenceChangeListener reported the change was successful. SharedPreferences is not recommended for storing data that is sensitive to this kind of rollback to a prior state such as user security or privacy settings. For other high-level data persistence options, see Room or DataStore.

Note: Common implementations guarantee that outstanding edits to preference files are persisted to disk when host Activities become stopped. In some situations (e.g. performing many Editor#commit() or Editor#apply() operations just prior to navigating away from the host Activity) this can lead to blocking the main thread during lifecycle transition events and associated ANR errors. For more details see the documentation for Editor#commit() and Editor#apply().

Note: This class does not support use across multiple processes.

Developer Guides

For more information about using SharedPreferences, read the Data Storage developer guide.

Summary

Nested classes

interface SharedPreferences.Editor

Interface used for modifying values in a SharedPreferences object. 

interface SharedPreferences.OnSharedPreferenceChangeListener

Interface definition for a callback to be invoked when a shared preference is changed. 

Public methods

abstract boolean contains(String key)

Checks whether the preferences contains a preference.

abstract SharedPreferences.Editor edit()

Create a new Editor for these preferences, through which you can make modifications to the data in the preferences and atomically commit those changes back to the SharedPreferences object.

abstract Map<String, ?> getAll()

Retrieve all values from the preferences.

abstract boolean getBoolean(String key, boolean defValue)

Retrieve a boolean value from the preferences.

abstract float getFloat(String key, float defValue)

Retrieve a float value from the preferences.

abstract int getInt(String key, int defValue)

Retrieve an int value from the preferences.

abstract long getLong(String key, long defValue)

Retrieve a long value from the preferences.

abstract String getString(String key, String defValue)

Retrieve a String value from the preferences.

abstract Set<String> getStringSet(String key, Set<String> defValues)

Retrieve a set of String values from the preferences.

abstract void registerOnSharedPreferenceChangeListener(SharedPreferences.OnSharedPreferenceChangeListener listener)

Registers a callback to be invoked when a change happens to a preference.

abstract void unregisterOnSharedPreferenceChangeListener(SharedPreferences.OnSharedPreferenceChangeListener listener)

Unregisters a previous callback.

Public methods

contains

Added in API level 1 
public abstract boolean contains (String key)

Checks whether the preferences contains a preference.

Parameters
key String: The name of the preference to check.
Returns
boolean Returns true if the preference exists in the preferences, otherwise false.

edit

Added in API level 1 
public abstract SharedPreferences.Editor edit ()

Create a new Editor for these preferences, through which you can make modifications to the data in the preferences and atomically commit those changes back to the SharedPreferences object.

Note that you must call Editor#commit to have any changes you perform in the Editor actually show up in the SharedPreferences.

Returns
SharedPreferences.Editor Returns a new instance of the Editor interface, allowing you to modify the values in this SharedPreferences object.

getAll

Added in API level 1 
public abstract Map<String, ?> getAll ()

Retrieve all values from the preferences.

Note that you must not modify the collection returned by this method, or alter any of its contents. The consistency of your stored data is not guaranteed if you do.

Returns
Map<String, ?> Returns a map containing a list of pairs key/value representing the preferences.
Throws
java.lang.NullPointerException

getBoolean

Added in API level 1 
public abstract boolean getBoolean (String key, 
                boolean defValue)

Retrieve a boolean value from the preferences.

Parameters
key String: The name of the preference to retrieve.
defValue boolean: Value to return if this preference does not exist.
Returns
boolean Returns the preference value if it exists, or defValue. Throws ClassCastException if there is a preference with this name that is not a boolean.
Throws
java.lang.ClassCastException

getFloat

Added in API level 1 
public abstract float getFloat (String key, 
                float defValue)

Retrieve a float value from the preferences.

Parameters
key String: The name of the preference to retrieve.
defValue float: Value to return if this preference does not exist.
Returns
float Returns the preference value if it exists, or defValue. Throws ClassCastException if there is a preference with this name that is not a float.
Throws
java.lang.ClassCastException

getInt

Added in API level 1 
public abstract int getInt (String key, 
                int defValue)

Retrieve an int value from the preferences.

Parameters
key String: The name of the preference to retrieve.
defValue int: Value to return if this preference does not exist.
Returns
int Returns the preference value if it exists, or defValue. Throws ClassCastException if there is a preference with this name that is not an int.
Throws
java.lang.ClassCastException

getLong

Added in API level 1 
public abstract long getLong (String key, 
                long defValue)

Retrieve a long value from the preferences.

Parameters
key String: The name of the preference to retrieve.
defValue long: Value to return if this preference does not exist.
Returns
long Returns the preference value if it exists, or defValue. Throws ClassCastException if there is a preference with this name that is not a long.
Throws
java.lang.ClassCastException

getString

Added in API level 1 
public abstract String getString (String key, 
                String defValue)

Retrieve a String value from the preferences.

Parameters
key String: The name of the preference to retrieve.
defValue String: Value to return if this preference does not exist. This value may be null.
Returns
String Returns the preference value if it exists, or defValue. Throws ClassCastException if there is a preference with this name that is not a String. This value may be null.
Throws
java.lang.ClassCastException

getStringSet

Added in API level 11 
public abstract Set<String> getStringSet (String key, 
                Set<String> defValues)

Retrieve a set of String values from the preferences.

Note that you must not modify the set instance returned by this call. The consistency of the stored data is not guaranteed if you do, nor is your ability to modify the instance at all.

Parameters
key String: The name of the preference to retrieve.
defValues Set: Values to return if this preference does not exist. This value may be null.
Returns
Set<String> Returns the preference values if they exist, or defValues. Throws ClassCastException if there is a preference with this name that is not a Set. This value may be null.
Throws
java.lang.ClassCastException

registerOnSharedPreferenceChangeListener

Added in API level 1 
public abstract void registerOnSharedPreferenceChangeListener (SharedPreferences.OnSharedPreferenceChangeListener listener)

Registers a callback to be invoked when a change happens to a preference.

Caution: The preference manager does not currently store a strong reference to the listener. You must store a strong reference to the listener, or it will be susceptible to garbage collection. We recommend you keep a reference to the listener in the instance data of an object that will exist as long as you need the listener.

Parameters
listener SharedPreferences.OnSharedPreferenceChangeListener: The callback that will run.

unregisterOnSharedPreferenceChangeListener

Added in API level 1 
public abstract void unregisterOnSharedPreferenceChangeListener (SharedPreferences.OnSharedPreferenceChangeListener listener)

Unregisters a previous callback.

Parameters
listener SharedPreferences.OnSharedPreferenceChangeListener: The callback that should be unregistered.