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1   /*
2    * Copyright (c) 2000, 2003, Oracle and/or its affiliates. All rights reserved.
3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4    *
5    * This code is free software; you can redistribute it and/or modify it
6    * under the terms of the GNU General Public License version 2 only, as
7    * published by the Free Software Foundation.  Oracle designates this
8    * particular file as subject to the "Classpath" exception as provided
9    * by Oracle in the LICENSE file that accompanied this code.
10   *
11   * This code is distributed in the hope that it will be useful, but WITHOUT
12   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14   * version 2 for more details (a copy is included in the LICENSE file that
15   * accompanied this code).
16   *
17   * You should have received a copy of the GNU General Public License version
18   * 2 along with this work; if not, write to the Free Software Foundation,
19   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20   *
21   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22   * or visit www.oracle.com if you need additional information or have any
23   * questions.
24   */
25  
26  package java.util.prefs;
27  
28  import java.io.NotSerializableException;
29  
30  /**
31   * An event emitted by a <tt>Preferences</tt> node to indicate that
32   * a preference has been added, removed or has had its value changed.<p>
33   *
34   * Note, that although PreferenceChangeEvent inherits Serializable interface
35   * from EventObject, it is not intended to be Serializable. Appropriate
36   * serialization methods are implemented to throw NotSerializableException.
37   *
38   * @author  Josh Bloch
39   * @see Preferences
40   * @see PreferenceChangeListener
41   * @see NodeChangeEvent
42   * @since   1.4
43   * @serial exclude
44   */
45  public class PreferenceChangeEvent extends java.util.EventObject {
46  
47      /**
48       * Key of the preference that changed.
49       *
50       * @serial
51       */
52      private String key;
53  
54      /**
55       * New value for preference, or <tt>null</tt> if it was removed.
56       *
57       * @serial
58       */
59      private String newValue;
60  
61      /**
62       * Constructs a new <code>PreferenceChangeEvent</code> instance.
63       *
64       * @param node  The Preferences node that emitted the event.
65       * @param key  The key of the preference that was changed.
66       * @param newValue  The new value of the preference, or <tt>null</tt>
67       *                  if the preference is being removed.
68       */
69      public PreferenceChangeEvent(Preferences node, String key,
70                                   String newValue) {
71          super(node);
72          this.key = key;
73          this.newValue = newValue;
74      }
75  
76      /**
77       * Returns the preference node that emitted the event.
78       *
79       * @return  The preference node that emitted the event.
80       */
81      public Preferences getNode() {
82          return (Preferences) getSource();
83      }
84  
85      /**
86       * Returns the key of the preference that was changed.
87       *
88       * @return  The key of the preference that was changed.
89       */
90      public String getKey() {
91          return key;
92      }
93  
94      /**
95       * Returns the new value for the preference.
96       *
97       * @return  The new value for the preference, or <tt>null</tt> if the
98       *          preference was removed.
99       */
100     public String getNewValue() {
101         return newValue;
102     }
103 
104     /**
105      * Throws NotSerializableException, since NodeChangeEvent objects
106      * are not intended to be serializable.
107      */
108      private void writeObject(java.io.ObjectOutputStream out)
109                                                throws NotSerializableException {
110          throw new NotSerializableException("Not serializable.");
111      }
112 
113     /**
114      * Throws NotSerializableException, since PreferenceChangeEvent objects
115      * are not intended to be serializable.
116      */
117      private void readObject(java.io.ObjectInputStream in)
118                                                throws NotSerializableException {
119          throw new NotSerializableException("Not serializable.");
120      }
121 
122     // Defined so that this class isn't flagged as a potential problem when
123     // searches for missing serialVersionUID fields are done.
124     private static final long serialVersionUID = 793724513368024975L;
125 }