/*

 * Copyright (c) 2000, 2003, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package java.util.prefs;

import java.io.NotSerializableException;

/**

 * An event emitted by a <tt>Preferences</tt> node to indicate that

 * a preference has been added, removed or has had its value changed.<p>

 *

 * Note, that although PreferenceChangeEvent inherits Serializable interface

 * from EventObject, it is not intended to be Serializable. Appropriate

 * serialization methods are implemented to throw NotSerializableException.

 *

 * @author  Josh Bloch

 * @see Preferences

 * @see PreferenceChangeListener

 * @see NodeChangeEvent

 * @since   1.4

 * @serial exclude

 */

public class PreferenceChangeEvent extends java.util.EventObject {

    /**

     * Key of the preference that changed.

     *

     * @serial

     */

    private String key;

    /**

     * New value for preference, or <tt>null</tt> if it was removed.

     *

     * @serial

     */

    private String newValue;

    /**

     * Constructs a new <code>PreferenceChangeEvent</code> instance.

     *

     * @param node  The Preferences node that emitted the event.

     * @param key  The key of the preference that was changed.

     * @param newValue  The new value of the preference, or <tt>null</tt>

     *                  if the preference is being removed.

     */

    public PreferenceChangeEvent(Preferences node, String key,

                                 String newValue) {

        super(node);

        this.key = key;

        this.newValue = newValue;

    }

    /**

     * Returns the preference node that emitted the event.

     *

     * @return  The preference node that emitted the event.

     */

    public Preferences getNode() {

        return (Preferences) getSource();

    }

    /**

     * Returns the key of the preference that was changed.

     *

     * @return  The key of the preference that was changed.

     */

    public String getKey() {

        return key;

    }

    /**

     * Returns the new value for the preference.

     *

     * @return  The new value for the preference, or <tt>null</tt> if the

     *          preference was removed.

     */

    public String getNewValue() {

        return newValue;

    }

    /**

     * Throws NotSerializableException, since NodeChangeEvent objects

     * are not intended to be serializable.

     */

     private void writeObject(java.io.ObjectOutputStream out)

                                               throws NotSerializableException {

         throw new NotSerializableException("Not serializable.");

     }

    /**

     * Throws NotSerializableException, since PreferenceChangeEvent objects

     * are not intended to be serializable.

     */

     private void readObject(java.io.ObjectInputStream in)

                                               throws NotSerializableException {

         throw new NotSerializableException("Not serializable.");

     }

    // Defined so that this class isn't flagged as a potential problem when

    // searches for missing serialVersionUID fields are done.

    private static final long serialVersionUID = 793724513368024975L;

}