Package androidx.databinding

Class CallbackRegistry<C,T,A>

java.lang.Object

androidx.databinding.CallbackRegistry<C,T,A>

Type Parameters:

C - The callback type.

T - The notification sender type. Typically this is the containing class.

A - Opaque argument used to pass additional data beyond an int.

All Implemented Interfaces:

java.lang.Cloneable

public class CallbackRegistry<C,T,A>
extends java.lang.Object
implements java.lang.Cloneable

A utility for storing and notifying callbacks. This class supports reentrant modification of the callbacks during notification without adversely disrupting notifications. A common pattern for callbacks is to receive a notification and then remove themselves. This class handles this behavior with constant memory under most circumstances.

A subclass of CallbackRegistry.NotifierCallback must be passed to the constructor to define how notifications should be called. That implementation does the actual notification on the listener. It is typically a static instance that can be reused for all similar CallbackRegistries.

This class supports only callbacks with at most three parameters. Typically, these are the notification originator and a parameter, with another to indicate which method to call, but these may be used as required. If more than three parameters are required or primitive types other than the single int provided must be used, A should be some kind of containing structure that the subclass may reuse between notifications.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	CallbackRegistry.NotifierCallback<C,T,A>	Class used to notify events from CallbackRegistry.

Constructor Summary

Constructors

Constructor	Description
CallbackRegistry(CallbackRegistry.NotifierCallback<C,T,A> notifier)	Creates an EventRegistry that notifies the event with notifier.

Method Summary

Modifier and Type	Method	Description
void	add(C callback)	Add a callback to be notified.
void	clear()	Removes all callbacks from the list.
CallbackRegistry<C,T,A>	clone()
java.util.ArrayList<C>	copyCallbacks()	Makes a copy of the registered callbacks and returns it.
void	copyCallbacks(java.util.List<C> callbacks)	Modifies callbacks to contain all callbacks in the CallbackRegistry.
boolean	isEmpty()	Returns true if there are no registered callbacks or false otherwise.
void	notifyCallbacks(T sender, int arg, A arg2)	Notify all callbacks.
void	remove(C callback)	Remove a callback.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CallbackRegistry

public CallbackRegistry(CallbackRegistry.NotifierCallback<C,T,A> notifier)

Creates an EventRegistry that notifies the event with notifier.

Parameters:

notifier - The class to use to notify events.

Method Detail

notifyCallbacks

public void notifyCallbacks(T sender,
                            int arg,
                            A arg2)

Notify all callbacks.

Parameters:

sender - The originator. This is an opaque parameter passed to CallbackRegistry.NotifierCallback.onNotifyCallback(Object, Object, int, Object)

arg - An opaque parameter passed to CallbackRegistry.NotifierCallback.onNotifyCallback(Object, Object, int, Object)

arg2 - An opaque parameter passed to CallbackRegistry.NotifierCallback.onNotifyCallback(Object, Object, int, Object)

add

public void add(C callback)

Add a callback to be notified. If the callback is already in the list, another won't be added. This does not affect current notifications.

Parameters:

callback - The callback to add.

remove

public void remove(C callback)

Remove a callback. This callback won't be notified after this call completes.

Parameters:

callback - The callback to remove.

copyCallbacks

public java.util.ArrayList<C> copyCallbacks()

Makes a copy of the registered callbacks and returns it.

Returns:

a copy of the registered callbacks.

copyCallbacks

public void copyCallbacks(java.util.List<C> callbacks)

Modifies callbacks to contain all callbacks in the CallbackRegistry.

Parameters:

callbacks - modified to contain all callbacks registered to receive events.

isEmpty

public boolean isEmpty()

Returns true if there are no registered callbacks or false otherwise.

Returns:

true if there are no registered callbacks or false otherwise.

clear

public void clear()

Removes all callbacks from the list.

clone

public CallbackRegistry<C,T,A> clone()

Overrides:

clone in class java.lang.Object

Returns:

A copy of the CallbackRegistry with all callbacks listening to both instances.