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 1.1
  37  */
  38 
  39 public class EventObject implements java.io.Serializable {
  40 
  41     @java.io.Serial
  42     private static final long serialVersionUID = 5516075349620653480L;
  43 
  44     /**
  45      * The object on which the Event initially occurred.
  46      */
  47     protected transient Object source;
  48 
  49     /**
  50      * Constructs a prototypical Event.
  51      *
  52      * @param source the object on which the Event initially occurred
  53      * @throws IllegalArgumentException if source is null
  54      */
  55     public EventObject(Object source) {
  56         if (source == null)
  57             throw new IllegalArgumentException("null source");
  58 
  59         this.source = source;
  60     }
  61 
  62     /**
  63      * The object on which the Event initially occurred.
  64      *
  65      * @return the object on which the Event initially occurred
  66      */
  67     public Object getSource() {
  68         return source;
  69     }
  70 
  71     /**
  72      * Returns a String representation of this EventObject.
  73      *
  74      * @return a String representation of this EventObject
  75      */
  76     public String toString() {
  77         return getClass().getName() + "[source=" + source + "]";
  78     }
  79 }