package org.jutil.event;import java.util.EventObject;/** * <p>This model type extends the Notifier contract, stating that only *   <code>null</code> is valid as event.</p> * <p>If your notifier only accepts <code>null</code> as valid events, *   you can simply model implement this type to inherit that contract. *   The implementation of {@link Notifier#notifyListner(EventListener, *   EventObject)} then can depend on the fact that it's event argument *   will be <code>null</code>, because this method is used as an abstract *   precondition. This extra contract will never be used, because a notifier that knows the event will be null, will never use the argument anyway, and thus does not rely on the actual value of the formal argument <code>event</code>. Any extra information about it is irrelevant. * @path    $Source: /cvsroot/org-jutil/jutil.org/src/org/jutil/event/NullEventReliancy.jml,v $ * @version $Revision: 1.5 $ * @date    $Date: 2002/08/24 13:52:24 $ * @state   $State: Exp $ * @author  Jan Dockx * @release $Name:  $ */public interface NullEventReliancy extends Notifier {	/* The revision of this class */	public final static String CVS_REVISION ="$Revision: 1.5 $";  /**   * If <formal_argument>event</formal_argument> is not null, this   * method will return false. If <formal_argument>event</formal_argument>   * is null, this method will return true. There is nothing more regarding   * the event that subtypes can demand.   */ /*@   @ also public behavior   @   @ post \result <==> (event == null);   @*/  public pure model boolean isValidEvent(EventObject event);}/* * <copyright>Copyright (C) 1997-2001. This software is copyrighted by  * the people and entities mentioned after the "@author" tags above, on  * behalf of the JUTIL.ORG Project. The copyright is dated by the dates  * after the "@date" tags above. All rights reserved. * This software is published under the terms of the JUTIL.ORG Software * License version 1.1 or later, a copy of which has been included with * this distribution in the LICENSE file, which can also be found at * http://org-jutil.sourceforge.net/LICENSE. This software is distributed  * WITHOUT ANY WARRANTY; without even the implied warranty of  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  * See the JUTIL.ORG Software License for more details. For more information, * please see http://org-jutil.sourceforge.net/</copyright>/ */