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.component;
020    
021    import java.util.EventObject;
022    
023    /**
024     * Event triggered as a result of a model change.
025     *
026     * @author <a href="http://www.dpml.net">Digital Product Meta Library</a>
027     * @version 1.0.0
028     */
029    public class ModelEvent extends EventObject
030    {
031       /**
032        * Serial version identifier.
033        */
034        static final long serialVersionUID = 1L;
035    
036        private final String m_feature;
037        private final Object m_from;
038        private final Object m_to;
039    
040       /**
041        * Construct a new <code>ModelEvent</code>.
042        *
043        * @param source the source component model
044        * @param feature the name of the model feature
045        * @param from the original value
046        * @param to the new value
047        */
048        public ModelEvent( final Model source, String feature, Object from, Object to )
049        {
050            super( source );
051            
052            m_feature = feature;
053            m_from = from;
054            m_to = to;
055        }
056    
057       /**
058        * Return the feature name.
059        * @return the name of the modified feature
060        */
061        public String getFeature()
062        {
063            return m_feature;
064        }
065    
066       /**
067        * Return the old value.
068        * @return the original value
069        */
070        public Object getOldValue()
071        {
072            return m_from;
073        }
074    
075       /**
076        * Return the new value.
077        * @return the new current value
078        */
079        public Object getNewValue()
080        {
081            return m_to;
082        }
083        
084       /**
085        * Return the component model that initiating the event.
086        * @return the source model
087        */
088        public Model getSourceModel()
089        {
090            return (Model) super.getSource();
091        }
092    }
093