246 lines
8.9 KiB
Java
246 lines
8.9 KiB
Java
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/*
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* java.beans.VetoableChangeSupport: part of the Java Class Libraries project.
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* Copyright (C) 1998 Free Software Foundation
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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package java.beans;
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import java.util.Hashtable;
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import java.util.Vector;
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/**
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** VetoableChangeSupport makes it easy to fire vetoable
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** change events and handle listeners as well as reversion
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** of old values when things go wrong.
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**
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** @author John Keiser
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** @since JDK1.1
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** @version 1.2.0, 15 Mar 1998
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**/
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public class VetoableChangeSupport implements java.io.Serializable {
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Hashtable propertyListeners = new Hashtable();
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Vector listeners = new Vector();
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Object bean;
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/** Create VetoableChangeSupport to work with a specific
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** source bean.
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** @param bean the source bean to use.
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**/
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public VetoableChangeSupport(Object bean) {
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this.bean = bean;
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}
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/** Adds a VetoableChangeListener to the list of listeners.
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** All property change events will be sent to this listener.
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** <P>
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**
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** The listener add is not unique: that is, <em>n</em> adds with
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** the same listener will result in <em>n</em> events being sent
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** to that listener for every property change.
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** <P>
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**
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** Adding a null listener will cause undefined behavior.
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**
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** @param l the listener to add.
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**/
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public void addVetoableChangeListener(VetoableChangeListener l) {
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listeners.addElement(l);
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}
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/** Adds a VetoableChangeListener listening on the specified property.
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** Events will be sent to the listener for that particular property.
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** <P>
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**
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** The listener add is not unique; that is, <em>n</em> adds on a
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** particular property for a particular listener will result in
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** <em>n</em> events being sent to that listener when that
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** property is changed.
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** <P>
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**
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** The effect is cumulative, too; if you are registered to listen
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** to receive events on all property changes, and then you
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** register on a particular property, you will receive change
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** events for that property twice.
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** <P>
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**
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** Adding a null listener will cause undefined behavior.
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**
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** @param propertyName the name of the property to listen on.
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** @param l the listener to add.
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**/
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public void addVetoableChangeListener(String propertyName, VetoableChangeListener l) {
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synchronized(propertyListeners) {
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Vector v = (Vector)propertyListeners.get(propertyName);
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try {
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v.addElement(l);
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} catch(NullPointerException e) {
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/* If v is not found, create a new vector. */
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v = new Vector();
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v.addElement(l);
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propertyListeners.put(propertyName, v);
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}
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}
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}
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/** Removes a VetoableChangeListener from the list of listeners.
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** If any specific properties are being listened on, they must
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** be deregistered by themselves; this will only remove the
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** general listener to all properties.
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** <P>
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**
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** If <code>add()</code> has been called multiple times for a
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** particular listener, <code>remove()</code> will have to be
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** called the same number of times to deregister it.
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**
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** @param l the listener to remove.
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**/
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public void removeVetoableChangeListener(VetoableChangeListener l) {
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listeners.removeElement(l);
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}
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/** Removes a VetoableChangeListener from listening to a specific property.
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** <P>
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**
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** If <code>add()</code> has been called multiple times for a
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** particular listener on a property, <code>remove()</code> will
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** have to be called the same number of times to deregister it.
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**
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** @param propertyName the property to stop listening on.
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** @param l the listener to remove.
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**/
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public void removeVetoableChangeListener(String propertyName, VetoableChangeListener l) {
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synchronized(propertyListeners) {
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Vector v = (Vector)propertyListeners.get(propertyName);
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try {
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v.removeElement(l);
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if(v.size() == 0) {
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propertyListeners.remove(propertyName);
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}
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} catch(NullPointerException e) {
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/* if v is not found, do nothing. */
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}
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}
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}
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/** Fire a VetoableChangeEvent to all the listeners.
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** If any listener objects, a reversion event will be sent to
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** those listeners who received the initial event.
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**
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** @param proposedChange the event to send.
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** @exception PropertyVetoException if the change is vetoed.
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**/
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public void fireVetoableChange(PropertyChangeEvent proposedChange) throws PropertyVetoException {
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int currentListener=0;
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try {
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for(;currentListener<listeners.size();currentListener++) {
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((VetoableChangeListener)listeners.elementAt(currentListener)).vetoableChange(proposedChange);
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}
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} catch(PropertyVetoException e) {
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PropertyChangeEvent reversion = new PropertyChangeEvent(proposedChange.getSource(),proposedChange.getPropertyName(),proposedChange.getNewValue(),proposedChange.getOldValue());
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for(int sendAgain=0;sendAgain<currentListener;sendAgain++) {
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try {
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((VetoableChangeListener)listeners.elementAt(sendAgain)).vetoableChange(reversion);
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} catch(PropertyVetoException e2) {
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}
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}
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throw e;
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}
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Vector moreListeners = (Vector)propertyListeners.get(proposedChange.getPropertyName());
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if(moreListeners != null) {
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try {
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for(currentListener = 0; currentListener < moreListeners.size(); currentListener++) {
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((VetoableChangeListener)moreListeners.elementAt(currentListener)).vetoableChange(proposedChange);
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}
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} catch(PropertyVetoException e) {
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PropertyChangeEvent reversion = new PropertyChangeEvent(proposedChange.getSource(),proposedChange.getPropertyName(),proposedChange.getNewValue(),proposedChange.getOldValue());
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for(int sendAgain=0;sendAgain<listeners.size();sendAgain++) {
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try {
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((VetoableChangeListener)listeners.elementAt(currentListener)).vetoableChange(proposedChange);
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} catch(PropertyVetoException e2) {
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}
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}
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for(int sendAgain=0;sendAgain<currentListener;sendAgain++) {
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try {
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((VetoableChangeListener)moreListeners.elementAt(sendAgain)).vetoableChange(reversion);
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} catch(PropertyVetoException e2) {
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}
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}
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throw e;
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}
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}
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}
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/** Fire a VetoableChangeEvent containing the old and new values of the property to all the listeners.
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** If any listener objects, a reversion event will be sent to
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** those listeners who received the initial event.
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**
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** @param propertyName the name of the property that
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** changed.
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** @param oldVal the old value.
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** @param newVal the new value.
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** @exception PropertyVetoException if the change is vetoed.
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**/
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public void fireVetoableChange(String propertyName, Object oldVal, Object newVal) throws PropertyVetoException {
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fireVetoableChange(new PropertyChangeEvent(bean,propertyName,oldVal,newVal));
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}
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/** Fire a VetoableChangeEvent containing the old and new values of the property to all the listeners.
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** If any listener objects, a reversion event will be sent to
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** those listeners who received the initial event.
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**
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** @param propertyName the name of the property that
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** changed.
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** @param oldVal the old value.
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** @param newVal the new value.
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** @exception PropertyVetoException if the change is vetoed.
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**/
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public void fireVetoableChange(String propertyName, boolean oldVal, boolean newVal) throws PropertyVetoException {
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fireVetoableChange(new PropertyChangeEvent(bean,propertyName,new Boolean(oldVal),new Boolean(newVal)));
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}
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/** Fire a VetoableChangeEvent containing the old and new values of the property to all the listeners.
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** If any listener objects, a reversion event will be sent to
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** those listeners who received the initial event.
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**
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** @param propertyName the name of the property that
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** changed.
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** @param oldVal the old value.
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** @param newVal the new value.
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** @exception PropertyVetoException if the change is vetoed.
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**/
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public void fireVetoableChange(String propertyName, int oldVal, int newVal) throws PropertyVetoException {
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fireVetoableChange(new PropertyChangeEvent(bean,propertyName,new Integer(oldVal),new Integer(newVal)));
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}
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/** Tell whether the specified property is being listened on or not.
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** This will only return <code>true</code> if there are listeners
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** on all properties or if there is a listener specifically on this
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** property.
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**
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** @param propertyName the property that may be listened on
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** @return whether the property is being listened on
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**/
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public boolean hasListeners(String propertyName) {
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return listeners.size() > 0 || propertyListeners.get(propertyName) != null;
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}
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}
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