/*

 * Copyright 1996-2003 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.util;

/**

 * <p>

 * The root class from which all event state objects shall be derived.

 * <p>

 * All Events are constructed with a reference to the object, the "source",

 * that is logically deemed to be the object upon which the Event in question

 * initially occurred upon.

 *

 * @since JDK1.1

 */

public class EventObject implements java.io.Serializable {

    private static final long serialVersionUID = 5516075349620653480L;

    /**

     * The object on which the Event initially occurred.

     */

    protected transient Object  source;

    /**

     * Constructs a prototypical Event.

     *

     * @param    source    The object on which the Event initially occurred.

     * @exception  IllegalArgumentException  if source is null.

     */

    public EventObject(Object source) {

        if (source == null)

            throw new IllegalArgumentException("null source");

        this.source = source;

    }

    /**

     * The object on which the Event initially occurred.

     *

     * @return   The object on which the Event initially occurred.

     */

    public Object getSource() {

        return source;

    }

    /**

     * Returns a String representation of this EventObject.

     *

     * @return  A a String representation of this EventObject.

     */

    public String toString() {

        return getClass().getName() + "[source=" + source + "]";

    }

}