001 /* VetoableChangeListenerProxy.java -- adds a name to a vetoable listener
002 Copyright (C) 2002, 2005 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.beans;
040
041 import java.util.EventListenerProxy;
042
043 /**
044 * This class provides an extension to <code>VetoableChangeListener</code> -
045 * associating a name with the listener. This can be used to filter the
046 * changes that one is interested in.
047 *
048 * @author Eric Blake (ebb9@email.byu.edu)
049 * @since 1.4
050 * @status udpated to 1.4
051 */
052 public class VetoableChangeListenerProxy extends EventListenerProxy
053 implements VetoableChangeListener
054 {
055 /**
056 * The name of the property to listen for. Package visible for use by
057 * VetoableChangeSupport.
058 */
059 final String propertyName;
060
061 /**
062 * Create a new proxy which filters property change events and only passes
063 * changes to the named property on to the delegate.
064 *
065 * @param propertyName the property's name to filter on
066 * @param listener the delegate listener
067 */
068 public VetoableChangeListenerProxy(String propertyName,
069 VetoableChangeListener listener)
070 {
071 super(listener);
072 this.propertyName = propertyName;
073 }
074
075 /**
076 * Forwards the event on to the delegate if the property name matches.
077 *
078 * @param event the event to pass on, if it meets the filter
079 * @throws NullPointerException if the delegate this was created with is null
080 * @throws PropertyVetoException if the change is vetoed by the listener
081 */
082 public void vetoableChange(PropertyChangeEvent event)
083 throws PropertyVetoException
084 {
085 // Note: Sun does not filter, under the assumption that since
086 // VetoableChangeSupport unwraps proxys, this method should never be
087 // called by normal use of listeners.
088 String name = event == null ? null : event.getPropertyName();
089 if (name == null ? propertyName == null : name.equals(propertyName))
090 ((VetoableChangeListener) getListener()).vetoableChange(event);
091 }
092
093 /**
094 * Gets the name of the property this proxy is filtering on.
095 *
096 * @return the property name
097 */
098 public String getPropertyName()
099 {
100 return propertyName;
101 }
102 } // class VetoableChangeListenerProxy