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 }