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