@UnstableApi
public final class ListenerSet<T extends Object>

A set of listeners.

Events are guaranteed to arrive in the order in which they happened even if a new event is triggered recursively from another listener.

Events are also guaranteed to be only sent to the listeners registered at the time the event was enqueued and haven't been removed since.

All methods must be called on the Looper passed to the constructor unless indicated otherwise.

Parameters
<T extends Object>

The listener type.

Summary

Nested types
public interface ListenerSet.Event<T>

An event sent to a listener.

An event sent to a listener when all other events sent during one Looper message queue iteration were handled by the listener.

Public constructors
ListenerSet(
    Looper looper,
    Clock clock,
    ListenerSet.IterationFinishedEvent<T> iterationFinishedEvent
)

Creates a new listener set.

Public methods
void
add(T listener)

Adds a listener to the set.
void

Removes all listeners from the set.
ListenerSet<T>
copy(
    Looper looper,
    ListenerSet.IterationFinishedEvent<T> iterationFinishedEvent
)

Copies the listener set.
ListenerSet<T>
copy(
    Looper looper,
    Clock clock,
    ListenerSet.IterationFinishedEvent<T> iterationFinishedEvent
)

Copies the listener set.
void

Notifies listeners of events previously enqueued with queueEvent.
void
queueEvent(int eventFlag, ListenerSet.Event<T> event)

Adds an event that is sent to the listeners when flushEvents is called.
void

Releases the set of listeners immediately.
void
remove(T listener)

Removes a listener from the set.
void
sendEvent(int eventFlag, ListenerSet.Event<T> event)

Queues a single event and immediately flushes the event queue to notify all listeners.
void
setThrowsWhenUsingWrongThread(boolean throwsWhenUsingWrongThread)

This method is deprecated.

Do not use this method and ensure all calls are made from the correct thread.
int

Returns the number of added listeners.

Public constructors

ListenerSet

public ListenerSet(
    Looper looper,
    Clock clock,
    ListenerSet.IterationFinishedEvent<T> iterationFinishedEvent
)

Creates a new listener set.

Parameters
Looper looper

A Looper used to call listeners on. The same Looper must be used to call all other methods of this class unless indicated otherwise.
Clock clock

A Clock.
ListenerSet.IterationFinishedEvent<T> iterationFinishedEvent

An IterationFinishedEvent sent when all other events sent during one Looper message queue iteration were handled by the listeners.

Public methods

add

public void add(T listener)

Adds a listener to the set.

If a listener is already present, it will not be added again.

This method can be called from any thread.

Parameters
T listener

The listener to be added.

clear

public void clear()

Removes all listeners from the set.

copy

public ListenerSet<T> copy(
    Looper looper,
    ListenerSet.IterationFinishedEvent<T> iterationFinishedEvent
)

Copies the listener set.

This method can be called from any thread.

Parameters
Looper looper

The new Looper for the copied listener set.
ListenerSet.IterationFinishedEvent<T> iterationFinishedEvent

The new IterationFinishedEvent sent when all other events sent during one Looper message queue iteration were handled by the listeners.
Returns
ListenerSet<T>

The copied listener set.

copy

public ListenerSet<T> copy(
    Looper looper,
    Clock clock,
    ListenerSet.IterationFinishedEvent<T> iterationFinishedEvent
)

Copies the listener set.

This method can be called from any thread.

Parameters
Looper looper

The new Looper for the copied listener set.
Clock clock

The new Clock for the copied listener set.
ListenerSet.IterationFinishedEvent<T> iterationFinishedEvent

The new IterationFinishedEvent sent when all other events sent during one Looper message queue iteration were handled by the listeners.
Returns
ListenerSet<T>

The copied listener set.

flushEvents

public void flushEvents()

Notifies listeners of events previously enqueued with queueEvent.

queueEvent

public void queueEvent(int eventFlag, ListenerSet.Event<T> event)

Adds an event that is sent to the listeners when flushEvents is called.

Parameters
int eventFlag

An integer indicating the type of the event, or INDEX_UNSET to report this event without flag.
ListenerSet.Event<T> event

The event.

release

public void release()

Releases the set of listeners immediately.

This will ensure no events are sent to any listener after this method has been called.

remove

public void remove(T listener)

Removes a listener from the set.

If the listener is not present, nothing happens.

Parameters
T listener

The listener to be removed.

sendEvent

public void sendEvent(int eventFlag, ListenerSet.Event<T> event)

Queues a single event and immediately flushes the event queue to notify all listeners.

Parameters
int eventFlag

An integer flag indicating the type of the event, or INDEX_UNSET to report this event without flag.
ListenerSet.Event<T> event

The event.

setThrowsWhenUsingWrongThread

public void setThrowsWhenUsingWrongThread(boolean throwsWhenUsingWrongThread)

Sets whether methods throw when using the wrong thread.

Do not use this method unless to support legacy use cases.

Parameters
boolean throwsWhenUsingWrongThread

Whether to throw when using the wrong thread.

size

public int size()

Returns the number of added listeners.