/* * @(#)AbstractActionPropertyChangeListener.java 1.11 03/12/19 * * Copyright 2004 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package javax.swing; import java.beans.PropertyChangeEvent; import java.beans.PropertyChangeListener; import java.lang.ref.WeakReference; import java.lang.ref.ReferenceQueue; /** * A package-private PropertyChangeListener which listens for * property changes on an Action and updates the properties * of an ActionEvent source. *
* 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 {@link java.beans.XMLEncoder}.
*
* @version 1.11 12/19/03
* @author Georges Saab
* @see AbstractButton
*/
abstract class AbstractActionPropertyChangeListener implements PropertyChangeListener {
private static ReferenceQueue queue;
private WeakReference target;
private Action action;
AbstractActionPropertyChangeListener(JComponent c, Action a) {
super();
setTarget(c);
this.action = a;
}
public void setTarget(JComponent c) {
if (queue==null) {
queue = new ReferenceQueue();
}
// Check to see whether any old buttons have
// been enqueued for GC. If so, look up their
// PCL instance and remove it from its Action.
OwnedWeakReference r;
while ( (r = (OwnedWeakReference)queue.poll()) != null) {
AbstractActionPropertyChangeListener oldPCL =
(AbstractActionPropertyChangeListener)r.getOwner();
Action oldAction = oldPCL.getAction();
if (oldAction!=null) {
oldAction.removePropertyChangeListener(oldPCL);
}
}
this.target = new OwnedWeakReference(c, queue, this);
}
public JComponent getTarget() {
return (JComponent)this.target.get();
}
public Action getAction() {
return action;
}
private static class OwnedWeakReference extends WeakReference {
private Object owner;
OwnedWeakReference(Object target, ReferenceQueue queue, Object owner) {
super(target, queue);
this.owner = owner;
}
public Object getOwner() {
return owner;
}
}
}