libjava/java/util/EventObject.java

   1 /* EventObject.java -- represents an event on an object
   2    Copyright (C) 1999, 2000, 2002, 2005  Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.util;
  40
  41 import java.io.Serializable;
  42
  43 /**
  44  * Represents Events fired by Objects.
  45  *
  46  * @author Eric Blake (ebb9@email.byu.edu)
  47  * @see EventListener
  48  * @since 1.1
  49  * @status updated to 1.4
  50  */
  51 public class EventObject implements Serializable
  52 {
  53   /**
  54    * Compatible with JDK 1.1+.
  55    */
  56   private static final long serialVersionUID = 5516075349620653480L;
  57
  58   /**
  59    * The source object; in other words, the object which this event takes
  60    * place on.
  61    */
  62   protected transient Object source;
  63
  64   /**
  65    * Constructs an EventObject with the specified source.
  66    *
  67    * @param source the source of the event
  68    * @throws IllegalArgumentException if source is null (This is not
  69    *         specified, but matches the behavior of the JDK)
  70    */
  71   public EventObject(Object source)
  72   {
  73     // This check for null is stupid, if you ask me, since source is
  74     // protected and non-final, so a subclass can set it to null later on.
  75     if (source == null)
  76       throw new IllegalArgumentException();
  77     this.source = source;
  78   }
  79
  80   /**
  81    * Returns the source of the event.
  82    *
  83    * @return the event source
  84    */
  85   public Object getSource()
  86   {
  87     return source;
  88   }
  89
  90   /**
  91    * Converts the event to a String. The format is not specified, but by
  92    * observation, the JDK uses:
  93    * <code>getClass().getName() + "[source=" + source + "]";</code>.
  94    *
  95    * @return String representation of the Event
  96    */
  97   public String toString()
  98   {
  99     return getClass().getName() + "[source=" + source + "]";
 100   }
 101 } // class EventObject