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 Management Laboratory</a>
028     * @version 2.0.2
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