java.lang.Object | +----com.sun.java.swing.event.EventListenerList
A class which holds a list of EventListeners. A single instance can be used to hold all listeners (of all types) for the instance using the lsit. It is the responsiblity 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 benefits which this class provides are that it is relatively cheap in the case of no listeners, and provides serialization for eventlistener lists in a single place, as well as a degree of MT safety (when used correctly). Usage example: Say one is defining a class which sends out FooEvents, and wantds 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 listenrList = new EventListnerList(); 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 Object[] listeners = listenerList.getListenerList(); // Process the listeners last to first, notifying // those that are interested in this event for (int i = listeners.length-2; i>=0; i-=2) { if (listeners[i]==FooListener.class) { // Lazily create the event: if (fooEvent == null) fooEvent = new FooEvent(this); ((FooListener)listeners[i+1]).fooXXX(fooEvent); } } }foo should be changed to the appropriate name, and Method 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 Swing1.0 applications. It will not be possible to load serialized Swing1.0 objects with future releases of Swing. The JDK1.2 release of Swing will be the compatibility baseline for the serialized form of Swing objects.
protected transient Object listenerList[]
public EventListenerList()
public Object[] getListenerList()
public int getListenerCount()
public int getListenerCount(Class t)
public synchronized void add(Class t, EventListener l)
public synchronized void remove(Class t, EventListener l)
public String toString()