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1   /*
2    * Copyright (c) 1996, 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;
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  }