1 /*

     2  * Copyright 1996-2003 Sun Microsystems, Inc.  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.  Sun designates this

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

     9  * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    22  * CA 95054 USA or visit www.sun.com if you need additional information or

    23  * have any questions.

    24  */

    25 

    26 package java.util;

    27 

    28 /**

    29  * <p>

    30  * The root class from which all event state objects shall be derived.

    31  * <p>

    32  * All Events are constructed with a reference to the object, the "source",

    33  * that is logically deemed to be the object upon which the Event in question

    34  * initially occurred upon.

    35  *

    36  * @since JDK1.1

    37  */

    38 

    39 public class EventObject implements java.io.Serializable {

    40 

    41     private static final long serialVersionUID = 5516075349620653480L;

    42 

    43     /**

    44      * The object on which the Event initially occurred.

    45      */

    46     protected transient Object  source;

    47 

    48     /**

    49      * Constructs a prototypical Event.

    50      *

    51      * @param    source    The object on which the Event initially occurred.

    52      * @exception  IllegalArgumentException  if source is null.

    53      */

    54     public EventObject(Object source) {

    55         if (source == null)

    56             throw new IllegalArgumentException("null source");

    57 

    58         this.source = source;

    59     }

    60 

    61     /**

    62      * The object on which the Event initially occurred.

    63      *

    64      * @return   The object on which the Event initially occurred.

    65      */

    66     public Object getSource() {

    67         return source;

    68     }

    69 

    70     /**

    71      * Returns a String representation of this EventObject.

    72      *

    73      * @return  A a String representation of this EventObject.

    74      */

    75     public String toString() {

    76         return getClass().getName() + "[source=" + source + "]";

    77     }

    78 }