src/share/classes/javax/swing/ActionPropertyChangeListener.java

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   1 /*
   2  * Copyright (c) 1999, 2011, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any


  33 /**
  34  * A package-private PropertyChangeListener which listens for
  35  * property changes on an Action and updates the properties
  36  * of an ActionEvent source.
  37  * <p>
  38  * Subclasses must override the actionPropertyChanged method,
  39  * which is invoked from the propertyChange method as long as
  40  * the target is still valid.
  41  * </p>
  42  * <p>
  43  * WARNING WARNING WARNING WARNING WARNING WARNING:<br>
  44  * Do NOT create an annonymous inner class that extends this!  If you do
  45  * a strong reference will be held to the containing class, which in most
  46  * cases defeats the purpose of this class.
  47  *
  48  * @param T the type of JComponent the underlying Action is attached to
  49  *
  50  * @author Georges Saab
  51  * @see AbstractButton
  52  */

  53 abstract class ActionPropertyChangeListener<T extends JComponent>
  54         implements PropertyChangeListener, Serializable {
  55     private static ReferenceQueue<JComponent> queue;
  56 
  57     // WeakReference's aren't serializable.
  58     private transient OwnedWeakReference<T> target;
  59     // The Component's that reference an Action do so through a strong
  60     // reference, so that there is no need to check for serialized.
  61     private Action action;
  62 
  63     private static ReferenceQueue<JComponent> getQueue() {
  64         synchronized(ActionPropertyChangeListener.class) {
  65             if (queue == null) {
  66                 queue = new ReferenceQueue<JComponent>();
  67             }
  68         }
  69         return queue;
  70     }
  71 
  72     public ActionPropertyChangeListener(T c, Action a) {


   1 /*
   2  * Copyright (c) 1999, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any


  33 /**
  34  * A package-private PropertyChangeListener which listens for
  35  * property changes on an Action and updates the properties
  36  * of an ActionEvent source.
  37  * <p>
  38  * Subclasses must override the actionPropertyChanged method,
  39  * which is invoked from the propertyChange method as long as
  40  * the target is still valid.
  41  * </p>
  42  * <p>
  43  * WARNING WARNING WARNING WARNING WARNING WARNING:<br>
  44  * Do NOT create an annonymous inner class that extends this!  If you do
  45  * a strong reference will be held to the containing class, which in most
  46  * cases defeats the purpose of this class.
  47  *
  48  * @param T the type of JComponent the underlying Action is attached to
  49  *
  50  * @author Georges Saab
  51  * @see AbstractButton
  52  */
  53 @SuppressWarnings("serial") // Bound of type variable  is not serializable across versions
  54 abstract class ActionPropertyChangeListener<T extends JComponent>
  55         implements PropertyChangeListener, Serializable {
  56     private static ReferenceQueue<JComponent> queue;
  57 
  58     // WeakReference's aren't serializable.
  59     private transient OwnedWeakReference<T> target;
  60     // The Component's that reference an Action do so through a strong
  61     // reference, so that there is no need to check for serialized.
  62     private Action action;
  63 
  64     private static ReferenceQueue<JComponent> getQueue() {
  65         synchronized(ActionPropertyChangeListener.class) {
  66             if (queue == null) {
  67                 queue = new ReferenceQueue<JComponent>();
  68             }
  69         }
  70         return queue;
  71     }
  72 
  73     public ActionPropertyChangeListener(T c, Action a) {