State.java revision 608:7e06bf1dcb09 
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
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24 */
25
26package 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 */
43public 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
57