001/* PreferenceChangeEvent - ObjectEvent fired when a Preferences entry changes
002   Copyright (C) 2001, 2006 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010 
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package java.util.prefs;
039
040import java.io.IOException;
041import java.io.NotSerializableException;
042import java.io.ObjectInputStream;
043import java.io.ObjectOutputStream;
044import java.util.EventObject;
045
046/**
047 * ObjectEvent fired when a Preferences entry changes.
048 * This event is generated when a entry is added, changed or removed.
049 * When an entry is removed then <code>getNewValue</code> will return null.
050 * <p>
051 * Preference change events are only generated for entries in one particular
052 * preference node. Notification of subnode addition/removal is given by a
053 * <code>NodeChangeEvent</code>.
054 * <p>
055 * Note that although this class is marked as serializable, attempts to
056 * serialize it will fail with NotSerializableException.
057 *
058 * @since 1.4
059 * @author Mark Wielaard (mark@klomp.org)
060 */
061public class PreferenceChangeEvent extends EventObject {
062
063  // We have this to placate the compiler.
064  private static final long serialVersionUID = 793724513368024975L;
065  
066    /**
067     * The key of the changed entry.
068     */
069    private final String key;
070
071    /**
072     * The new value of the changed entry, or null when the entry was removed.
073     */
074    private final String newValue;
075
076    /**
077     * Creates a new PreferenceChangeEvent.
078     *
079     * @param node The source preference node for which an entry was added,
080     * changed or removed
081     * @param key The key of the entry that was added, changed or removed
082     * @param value The new value of the entry that was added or changed, or
083     * null when the entry was removed
084     */
085    public PreferenceChangeEvent(Preferences node, String key, String value) {
086        super(node);
087        this.key = key;
088        this.newValue = value;
089    }
090
091    /**
092     * Returns the source Preference node from which an entry was added,
093     * changed or removed.
094     */
095    public Preferences getNode() {
096        return (Preferences) source;
097    }
098
099    /**
100     * Returns the key of the entry that was added, changed or removed.
101     */
102    public String getKey() {
103        return key;
104    }
105
106    /**
107     * Returns the new value of the entry that was added or changed, or
108     * returns null when the entry was removed.
109     */
110    public String getNewValue() {
111        return newValue;
112    }
113
114    private void readObject(ObjectInputStream ois)
115      throws IOException
116    {
117      throw new NotSerializableException("LineEvent is not serializable");
118    }
119  
120    private void writeObject(ObjectOutputStream oos)
121      throws IOException
122    {
123      throw new NotSerializableException("LineEvent is not serializable");
124    }
125}