Package org.jdesktop.swingx.event
Class WeakEventListenerList
java.lang.Object
org.jdesktop.swingx.event.WeakEventListenerList
- All Implemented Interfaces:
Serializable
A class that holds a list of EventListeners. A single instance
can be used to hold all listeners (of all types) for the instance
using the list. It is the responsibility of the class using the
EventListenerList to provide type-safe API (preferably conforming
to the JavaBeans spec) and methods which dispatch event notification
methods to appropriate Event Listeners on the list.
The main benefit that this class provides is that it releases
garbage collected listeners (internally uses weak references).
PENDING: serialization support Usage example: Say one is defining a class that sends out FooEvents, and one wants to allow users of the class to register FooListeners and receive notification when FooEvents occur. The following should be added to the class definition:
EventListenerList listenerList = new EventListenerList(); FooEvent fooEvent = null; public void addFooListener(FooListener l) { listenerList.add(FooListener.class, l); } public void removeFooListener(FooListener l) { listenerList.remove(FooListener.class, l); } // Notify all listeners that have registered interest for // notification on this event type. The event instance // is lazily created using the parameters passed into // the fire method. protected void fireFooXXX() { // Guaranteed to return a non-null array FooListener[] listeners = listenerList.getListeners(FooListener.class); // Process the listeners last to first, notifying // those that are interested in this event for (FooListener listener: listeners) { // Lazily create the event: if (fooEvent == null) fooEvent = new FooEvent(this); listener.fooXXX(fooEvent); } } }foo should be changed to the appropriate name, and fireFooXxx to the appropriate method name. One fire method should exist for each notification method in the FooListener interface.
Warning:
Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is
appropriate for short term storage or RMI between applications running
the same version of Swing. As of 1.4, support for long term storage
of all JavaBeansTM
has been added to the java.beans
package.
Please see XMLEncoder
.
- Version:
- 1.37 11/17/05
- See Also:
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Field Summary
FieldsModifier and TypeFieldDescriptionprotected List
<Class<? extends EventListener>> protected List
<WeakReference<? extends EventListener>> -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescription<T extends EventListener>
voidAdds the listener as a listener of the specified type.private <T extends EventListener>
List<T> Returns a list of strongly referenced EventListeners.private List
<Class<? extends EventListener>> Object[]
Passes back the event listener list as an array of ListenerType-listener pairs.<T extends EventListener>
T[]getListeners
(Class<T> t) Return an array of all the listeners of the given type.private List
<WeakReference<? extends EventListener>> <T extends EventListener>
voidRemoves the listener as a listener of the specified type.
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Field Details
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weakReferences
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classes
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Constructor Details
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WeakEventListenerList
public WeakEventListenerList()
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Method Details
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getListenerList
Passes back the event listener list as an array of ListenerType-listener pairs. As a side-effect, cleans out any garbage collected listeners before building the array.- Returns:
- a array of listenerType-listener pairs.
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cleanReferences
Returns a list of strongly referenced EventListeners. Removes internal weak references to garbage collected listeners.- Returns:
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getReferences
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getClasses
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getListeners
Return an array of all the listeners of the given type. As a side-effect, cleans out any garbage collected listeners before building the array.- Returns:
- all of the listeners of the specified type.
- Throws:
ClassCastException
- if the supplied class is not assignable to EventListener- Since:
- 1.3
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add
Adds the listener as a listener of the specified type. As a side-effect, cleans out any garbage collected listeners before adding.- Parameters:
t
- the type of the listener to be addedl
- the listener to be added
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remove
Removes the listener as a listener of the specified type.- Parameters:
t
- the type of the listener to be removedl
- the listener to be removed
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