Source for java.util.EventObject

   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., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 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