001 /* 002 * Copyright 2005 Stephen J. McConnell. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or 013 * implied. 014 * 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018 019 package net.dpml.state; 020 021 import java.util.EventObject; 022 023 024 /** 025 * Event triggered as a result of a state change. 026 * 027 * @author <a href="http://www.dpml.net">Digital Product Meta Library</a> 028 * @version 1.0.4 029 */ 030 public class StateEvent extends EventObject 031 { 032 /** 033 * Serial version identifier. 034 */ 035 static final long serialVersionUID = 1L; 036 037 private final State m_from; 038 private final State m_to; 039 040 /** 041 * Construct a new <code>StateEvent</code>. 042 * 043 * @param source the source compoent model 044 * @param from the originating state 045 * @param to the new current state 046 */ 047 public StateEvent( final Object source, State from, State to ) 048 { 049 super( source ); 050 m_from = from; 051 m_to = to; 052 } 053 054 /** 055 * Return the state that existed prior to the transition. 056 * @return the original state 057 */ 058 public State getFromState() 059 { 060 return m_from; 061 } 062 063 /** 064 * Return the state that was established by a transition. 065 * @return the new current state 066 */ 067 public State getToState() 068 { 069 return m_to; 070 } 071 072 } 073