1 /*
   2  * Copyright (c) 1997, 2002, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.awt;
  27 
  28 /**
  29  * An interface for events that know how to dispatch themselves.
  30  * By implementing this interface an event can be placed upon the event
  31  * queue and its <code>dispatch()</code> method will be called when the event
  32  * is dispatched, using the <code>EventDispatchThread</code>.
  33  * <p>
  34  * This is a very useful mechanism for avoiding deadlocks. If
  35  * a thread is executing in a critical section (i.e., it has entered
  36  * one or more monitors), calling other synchronized code may
  37  * cause deadlocks. To avoid the potential deadlocks, an
  38  * <code>ActiveEvent</code> can be created to run the second section of
  39  * code at later time. If there is contention on the monitor,
  40  * the second thread will simply block until the first thread
  41  * has finished its work and exited its monitors.
  42  * <p>
  43  * For security reasons, it is often desirable to use an <code>ActiveEvent</code>
  44  * to avoid calling untrusted code from a critical thread. For
  45  * instance, peer implementations can use this facility to avoid
  46  * making calls into user code from a system thread. Doing so avoids
  47  * potential deadlocks and denial-of-service attacks.
  48  *
  49  * @author  Timothy Prinzing
  50  * @since   1.2
  51  */
  52 public interface ActiveEvent {
  53 
  54     /**
  55      * Dispatch the event to its target, listeners of the events source,
  56      * or do whatever it is this event is supposed to do.
  57      */
  58     public void dispatch();
  59 }
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