001/* EventObject.java -- represents an event on an object
002   Copyright (C) 1999, 2000, 2002, 2005  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.util;
040
041import java.io.Serializable;
042
043/**
044 * Represents Events fired by Objects.
045 *
046 * @author Eric Blake (ebb9@email.byu.edu)
047 * @see EventListener
048 * @since 1.1
049 * @status updated to 1.4
050 */
051public class EventObject implements Serializable
052{
053  /**
054   * Compatible with JDK 1.1+.
055   */
056  private static final long serialVersionUID = 5516075349620653480L;
057
058  /**
059   * The source object; in other words, the object which this event takes
060   * place on.
061   */
062  protected transient Object source;
063
064  /**
065   * Constructs an EventObject with the specified source.
066   *
067   * @param source the source of the event
068   * @throws IllegalArgumentException if source is null (This is not
069   *         specified, but matches the behavior of the JDK)
070   */
071  public EventObject(Object source)
072  {
073    // This check for null is stupid, if you ask me, since source is
074    // protected and non-final, so a subclass can set it to null later on.
075    if (source == null)
076      throw new IllegalArgumentException();
077    this.source = source;
078  }
079
080  /**
081   * Returns the source of the event.
082   *
083   * @return the event source
084   */
085  public Object getSource()
086  {
087    return source;
088  }
089
090  /**
091   * Converts the event to a String. The format is not specified, but by
092   * observation, the JDK uses:
093   * <code>getClass().getName() + "[source=" + source + "]";</code>.
094   *
095   * @return String representation of the Event
096   */
097  public String toString()
098  {
099    return getClass().getName() + "[source=" + source + "]";
100  }
101} // class EventObject