01 /*
02 * Copyright 1996-2003 Sun Microsystems, Inc. All Rights Reserved.
03 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
04 *
05 * This code is free software; you can redistribute it and/or modify it
06 * under the terms of the GNU General Public License version 2 only, as
07 * published by the Free Software Foundation. Sun designates this
08 * particular file as subject to the "Classpath" exception as provided
09 * 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 }
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