Package org.nuxeo.common.collections

Class ListenerList

java.lang.Object

org.nuxeo.common.collections.ListenerList

public class ListenerList
extends Object

Internal class to maintain a list of listeners. This class is a thread-safe list that is optimized for frequent reads and infrequent writes. Copy on write is used to ensure readers can access the list without synchronization overhead. Readers are given access to the underlying array data structure for reading, with the trust that they will not modify the underlying array.

Contains code from Eclipse org.eclipse.core.runtime.ListenerList class

See Also:

Eclipse.org

Field Summary

Fields

Modifier and Type	Field	Description
static int	EQUALITY	Mode constant (value 0) indicating that listeners should be compared using equality.
static int	IDENTITY	Mode constant (value 1) indicating that listeners should be compared using identity.

Constructor Summary

Constructors

Constructor	Description
ListenerList()	Creates a listener list.
ListenerList(int mode, Comparator<?> comparator)	Creates a listener list using the provided comparison mode.
ListenerList(Comparator<?> comparator)

Method Summary

Modifier and Type	Method	Description
void	add(Object listener)	Adds the given listener to this list.
Object[]	getListeners()	Returns an array containing all the registered listeners.
Object[]	getListenersCopy()
boolean	isEmpty()	Returns whether this listener list is empty.
void	remove(Object listener)	Removes the given listener from this list.
int	size()	Returns the number of registered listeners.

Methods inherited from class java.lang.Object

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

Field Detail

EQUALITY

public static final int EQUALITY

Mode constant (value 0) indicating that listeners should be compared using equality.

See Also:

Constant Field Values

IDENTITY

public static final int IDENTITY

Mode constant (value 1) indicating that listeners should be compared using identity.

See Also:

Constant Field Values

Constructor Detail

ListenerList

public ListenerList()

Creates a listener list.

ListenerList

public ListenerList(Comparator<?> comparator)

ListenerList

public ListenerList(int mode,
                    Comparator<?> comparator)

Creates a listener list using the provided comparison mode.

Method Detail

add

public void add(Object listener)

Adds the given listener to this list. Has no effect if an equal listener is already registered.

This method is synchronized to protect against multiple threads adding or removing listeners concurrently. This does not block concurrent readers.

Parameters:

listener - the listener to add

getListeners

public Object[] getListeners()

Returns an array containing all the registered listeners. The resulting array is unaffected by subsequent adds or removes. If there are no listeners registered, the result is an empty array singleton instance (no garbage is created). Use this method when notifying listeners, so that any modifications to the listener list during the notification will have no effect on the notification itself.

Note: callers must not modify the returned array.

Returns:

the list of registered listeners

getListenersCopy

public Object[] getListenersCopy()

isEmpty

public boolean isEmpty()

Returns whether this listener list is empty.

Returns:

true if there are no registered listeners, and false otherwise

remove

public void remove(Object listener)

Removes the given listener from this list. Has no effect if an identical listener was not already registered.

This method is synchronized to protect against multiple threads adding or removing listeners concurrently. This does not block concurrent readers.

Parameters:

listener - the listener

size

public int size()

Returns the number of registered listeners.

Returns:

the number of registered listeners