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      1 /* Licensed to the Apache Software Foundation (ASF) under one or more
      2  * contributor license agreements.  See the NOTICE file distributed with
      3  * this work for additional information regarding copyright ownership.
      4  * The ASF licenses this file to You under the Apache License, Version 2.0
      5  * (the "License"); you may not use this file except in compliance with
      6  * the License.  You may obtain a copy of the License at
      7  *
      8  *     http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package java.util.prefs;
     18 
     19 import java.io.IOException;
     20 import java.io.NotSerializableException;
     21 import java.io.ObjectInputStream;
     22 import java.io.ObjectOutputStream;
     23 import java.io.Serializable;
     24 import java.util.EventObject;
     25 
     26 /**
     27  * This is the event class to indicate that a preference has been added, deleted
     28  * or updated.
     29  * <p>
     30  * Please note that although the class is marked as {@code Serializable} by
     31  * inheritance from {@code EventObject}, this type is not intended to be serialized
     32  * so the serialization methods do nothing but throw a {@code NotSerializableException}.
     33  *
     34  * @see java.util.prefs.Preferences
     35  * @see java.util.prefs.PreferenceChangeListener
     36  *
     37  * @since 1.4
     38  */
     39 public class PreferenceChangeEvent extends EventObject implements Serializable {
     40 
     41     private static final long serialVersionUID = 793724513368024975L;
     42 
     43     private final Preferences node;
     44 
     45     private final String key;
     46 
     47     private final String value;
     48 
     49     /**
     50      * Construct a new {@code PreferenceChangeEvent} instance.
     51      *
     52      * @param p
     53      *            the {@code Preferences} instance that fired this event; this object is
     54      *            considered as the event's source.
     55      * @param k
     56      *            the changed preference key.
     57      * @param v
     58      *            the new value of the changed preference, this value can be
     59      *            {@code null}, which means the preference has been removed.
     60      */
     61     public PreferenceChangeEvent(Preferences p, String k, String v) {
     62         super(p);
     63         node = p;
     64         key = k;
     65         value = v;
     66     }
     67 
     68     /**
     69      * Gets the key of the changed preference.
     70      *
     71      * @return the changed preference's key.
     72      */
     73     public String getKey() {
     74         return key;
     75     }
     76 
     77     /**
     78      * Gets the new value of the changed preference or {@code null} if the
     79      * preference has been removed.
     80      *
     81      * @return the new value of the changed preference or {@code null} if the
     82      *         preference has been removed.
     83      */
     84     public String getNewValue() {
     85         return value;
     86     }
     87 
     88     /**
     89      * Gets the {@code Preferences} instance that fired this event.
     90      *
     91      * @return the {@code Preferences} instance that fired this event.
     92      */
     93     public Preferences getNode() {
     94         return node;
     95     }
     96 
     97     /**
     98      * This method always throws a <code>NotSerializableException</code>,
     99      * because this object cannot be serialized,
    100      */
    101     private void writeObject(ObjectOutputStream out) throws IOException {
    102         throw new NotSerializableException();
    103     }
    104 
    105     /**
    106      * This method always throws a <code>NotSerializableException</code>,
    107      * because this object cannot be serialized,
    108      */
    109     private void readObject(ObjectInputStream in) throws IOException{
    110         throw new NotSerializableException();
    111     }
    112 }
    113