1 /*
   2  * Copyright (c) 2002, 2003, 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 com.sun.corba.se.spi.orbutil.fsm ;
  27 
  28 /**
  29  * This interface must be implemented by any class that is used as
  30  * a state in a FSM.  The FSM only needs the identity of this
  31  * object, so all that is really needs is the default equals implementation.
  32  * The toString() method should also be overridden to give a concise
  33  * description or name of the state.  The StateImpl class handles this.
  34  * <P>
  35  * Pre- and post- actions are taken only on completed transitions between
  36  * different states.  Assume that the FSM is in state A, and the FSM will
  37  * transition to state B under input I with action X.  If A != B and X completes
  38  * successfully, then after X completes execution, A.postAction is executed,
  39  * followed by B.preAction.
  40  *
  41  * @author Ken Cavanaugh
  42  */
  43 public interface State
  44 {
  45     /** Method that defines action that occurs whenever this state is entered.
  46     * Any exceptions thrown by this method are ignored.
  47     */
  48     void preAction( FSM fsm ) ;
  49 
  50     /** Method that defines action that occurs whenever this state is exited.
  51     * Any exceptions thrown by this method are ignored.
  52     */
  53     void postAction( FSM fsm ) ;
  54 }
  55 
  56 // end of State.java