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.io.Serializable;
022    
023    /**
024     * Default implementation of trigger.
025     * 
026     * @author <a href="http://www.dpml.net">Digital Product Meta Library</a>
027     * @version 1.0.1
028     */
029    public class DefaultTrigger implements Trigger, Serializable
030    {
031        private final TriggerEvent m_event;
032        private final Action m_action;
033        
034       /**
035        * Creation of a new trigger.
036        * @param event the trigger event constant
037        * @param action the action fired by the trigger
038        */
039        public DefaultTrigger( final TriggerEvent event, final Action action )
040        {
041            if( null == event )
042            {
043                throw new NullPointerException( "event" );
044            }
045            if( null == action )
046            {
047                throw new NullPointerException( "action" );
048            }
049            m_event = event;
050            m_action = action;
051        }
052        
053       /**
054        * Return the event enumneration that this trigger is associated with.
055        * @return the triggering event class
056        */
057        public TriggerEvent getEvent()
058        {
059            return m_event;
060        }
061        
062       /**
063        * Return the actions  that this trigger initiates.
064        * @return the triggered action
065        */
066        public Action getAction()
067        {
068            return m_action;
069        }
070        
071       /**
072        * Compare this object to another for equality.
073        * @param other the other object
074        * @return true if the object is equal to this object
075        */
076        public boolean equals( Object other )
077        {
078            if( null == other )
079            {
080                return false;
081            }
082            else if( other instanceof DefaultTrigger )
083            {
084                DefaultTrigger trigger = (DefaultTrigger) other;
085                if( !m_event.equals( trigger.getEvent() ) )
086                {
087                    return false;
088                }
089                else
090                {
091                    return m_action.equals( trigger.getAction() );
092                }
093            }
094            else
095            {
096                return false;
097            }
098        }
099        
100       /**
101        * Compute the hashcode for this instance.
102        * @return the hashcode value
103        */
104        public int hashCode()
105        {
106            int hash = m_event.hashCode();
107            hash ^= m_action.hashCode();
108            return hash;
109        }
110    
111       /**
112        * Return a string representation of the instance.
113        * @return the string value
114        */
115        public String toString()
116        {
117            return "trigger:" + m_event.getName();
118        }
119    }