EventObject.java   [plain text]

/* EventObject.java -- represents an event on an object
   Copyright (C) 1999, 2000, 2002 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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02111-1307 USA.

Linking this library statically or dynamically with other modules is
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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this exception to your version of the library, but you are not
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exception statement from your version. */


package java.util;

import java.io.Serializable;

/**
 * Represents Events fired by Objects.
 *
 * @author Eric Blake <ebb9@email.byu.edu>
 * @see EventListener
 * @since 1.1
 * @status updated to 1.4
 */
public class EventObject implements Serializable
{
  /**
   * Compatible with JDK 1.1+.
   */
  private static final long serialVersionUID = 5516075349620653480L;

  /**
   * The source object; in other words, the object which this event takes
   * place on.
   */
  protected transient Object source;

  /**
   * Constructs an EventObject with the specified source.
   *
   * @param source the source of the event
   * @throws IllegalArgumentException if source is null (This is not
   *         specified, but matches the behavior of the JDK)
   */
  public EventObject(Object source)
  {
    // This check for null is stupid, if you ask me, since source is
    // protected and non-final, so a subclass can set it to null later on.
    if (source == null)
      throw new IllegalArgumentException();
    this.source = source;
  }

  /**
   * Returns the source of the event.
   *
   * @return the event source
   */
  public Object getSource()
  {
    return source;
  }

  /**
   * Converts the event to a String. The format is not specified, but by
   * observation, the JDK uses:
   * <code>getClass().getName() + "[source=" + source + "]";</code>.
   *
   * @return String representation of the Event
   */
  public String toString()
  {
    return getClass().getName() + "[source=" + source + "]";
  }
} // class EventObject