001    /* PreferenceChangeEvent - ObjectEvent fired when a Preferences entry changes
002       Copyright (C) 2001, 2006 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    package java.util.prefs;
039    
040    import java.io.IOException;
041    import java.io.NotSerializableException;
042    import java.io.ObjectInputStream;
043    import java.io.ObjectOutputStream;
044    import 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     */
061    public 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    }