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300 lines
11 KiB
Java
300 lines
11 KiB
Java
/* java.beans.VetoableChangeSupport
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Copyright (C) 1998 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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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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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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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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import java.util.Enumeration;
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import java.io.ObjectInputStream;
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import java.io.ObjectOutputStream;
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import java.io.IOException;
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import java.io.Serializable;
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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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transient Hashtable propertyListeners = new Hashtable();
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transient Vector listeners = new Vector();
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Hashtable children;
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Object source;
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int vetoableChangeSupportSerializedDataVersion = 2;
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private static final long serialVersionUID = -5090210921595982017L;
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/**
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* Saves the state of the object to the stream. */
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private void writeObject(ObjectOutputStream stream) throws IOException {
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children = propertyListeners.isEmpty() ? null : propertyListeners;
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stream.defaultWriteObject();
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for (Enumeration e = listeners.elements(); e.hasMoreElements(); ) {
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VetoableChangeListener l = (VetoableChangeListener)e.nextElement();
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if (l instanceof Serializable)
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stream.writeObject(l);
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}
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stream.writeObject(null);
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}
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/**
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* Reads the object back from stream (deserialization).
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*/
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private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
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stream.defaultReadObject();
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propertyListeners = (children == null) ? new Hashtable() : children;
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VetoableChangeListener l;
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while ((l = (VetoableChangeListener)stream.readObject()) != null) {
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addVetoableChangeListener(l);
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}
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// FIXME: XXX: There is no spec for JDK 1.1 serialization
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// so it is unclear what to do if the value of
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// vetoableChangeSupportSerializedDataVersion is 1.
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}
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/** Create VetoableChangeSupport to work with a specific
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** source bean.
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** @param source the source bean to use.
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**/
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public VetoableChangeSupport(Object source) {
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this.source = source;
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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(source,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(source,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(source,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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