001    /*
002     * Copyright 2004 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.metro.data;
020    
021    import net.dpml.component.Directive;
022    
023    /**
024     * A <code>NullDirective</code> is used to mark a solution as resolved
025     * on the basis that the solution will be managed by an enclosing component.
026     *
027     * @author <a href="http://www.dpml.net">Digital Product Meta Library</a>
028     * @version 1.0.1
029     */
030    public class NullDirective extends AbstractDirective implements Directive
031    {
032       /**
033        * Serial version identifier.
034        */
035        static final long serialVersionUID = 1L;
036    
037        //--------------------------------------------------------------------------
038        // constructors
039        //--------------------------------------------------------------------------
040    
041       /**
042        * Create a new null directive.
043        */
044        public NullDirective()
045        {
046        }
047    
048        //--------------------------------------------------------------------------
049        // NullDirective
050        //--------------------------------------------------------------------------
051    
052       /**
053        * Test if the supplied object is equal to this object.
054        * @param other the object to compare with this instance
055        * @return TRUE if the supplied object is equal to this object
056        */
057        public boolean equals( Object other )
058        {
059            if( null == other )
060            { 
061                return false;
062            }
063            else
064            {
065                return ( other instanceof NullDirective );
066            }
067        }
068    
069       /**
070        * Return the hashcode for the instance.
071        * @return the instance hashcode
072        */
073        public int hashCode()
074        {
075            return getClass().hashCode();
076        }
077    }