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  /*
   * @(#)WeakPropertyChangeListener.java
   * 
    * Copyright (c) 2011 Werner Randelshofer, Goldau, Switzerland.
   * All rights reserved.
   * 
   * You may not use, copy or modify this file, except in compliance with the
   * license agreement you entered into with Werner Randelshofer.
   * For details see accompanying license terms.
  *
  * This class has been derived from WeakPropertyChangeListener.java,
  * v 1.2 2005-06-20 18:26:16 by Paul Speed.
  *
  * Copyright (c) 2004, Paul Speed
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1) Redistributions of source code must retain the above copyright notice,
  *    this list of conditions and the following disclaimer.
  * 2) Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  * 3) Neither the names "Progeeks", "Meta-JB", nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */
 package org.monte.media.beans;
 
 import java.beans.*;
Property change listener that holds weak reference to a target property change listener. If the weak reference becomes null (meaning the delegate has been GC'ed) then this listener will remove itself from any beans that it receives events from. It isn't perfect, but it's a lot better than nothing... and presumably beans that no longer send out events probably don't care if their listeners weren't properly cleaned up. Design pattern: Proxy.

Author(s):
Paul Speed
Version:
$Id: WeakPropertyChangeListener.java 299 2013-01-03 07:40:18Z werner $
 
 public class WeakPropertyChangeListener implements PropertyChangeListener {
 
         this. = new WeakReference<PropertyChangeListener>(target);
     }

    
Method that can be subclassed to provide additional remove support. Default implementation only supports StandardBeans.
 
     protected void removeFromSource(PropertyChangeEvent event) {
         // Remove ourselves from the source
         Object src = event.getSource();
         try {
             src.getClass().getMethod("removePropertyChangeListener"new Class[] {PropertyChangeListener.class}).invoke(srcthis);
         } catch (Exception ex) {
             InternalError ie = new InternalError("Could not remove WeakPropertyChangeListener from "+src+".");
             ie.initCause(ex);
             throw ie;
         }
     }
 
     @Override
     public void propertyChange(PropertyChangeEvent event) {
         PropertyChangeListener listener = (PropertyChangeListener.get();
         if (listener == null) {
             removeFromSource(event);
             return;
         }
         listener.propertyChange(event);
     }

    
Returns the target of this proxy. Returns null if the target has been garbage collected.

Returns:
The target or null.
    public PropertyChangeListener getTarget() {
        return .get();
    }
    @Override
    public String toString() {
        return super.toString()+"["+.get()+"]";
    }
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