001    /*
002     *  Licensed to the Apache Software Foundation (ASF) under one
003     *  or more contributor license agreements.  See the NOTICE file
004     *  distributed with this work for additional information
005     *  regarding copyright ownership.  The ASF licenses this file
006     *  to you under the Apache License, Version 2.0 (the
007     *  "License"); you may not use this file except in compliance
008     *  with the License.  You may obtain a copy of the License at
009     *  
010     *    http://www.apache.org/licenses/LICENSE-2.0
011     *  
012     *  Unless required by applicable law or agreed to in writing,
013     *  software distributed under the License is distributed on an
014     *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     *  KIND, either express or implied.  See the License for the
016     *  specific language governing permissions and limitations
017     *  under the License. 
018     *  
019     */
020    
021    package org.apache.directory.server.dns.util;
022    
023    
024    import java.util.HashMap;
025    import java.util.Map;
026    
027    import org.apache.directory.server.i18n.I18n;
028    
029    
030    /**
031     * A map to easily get the actual Enum instance from it's value as seen in the
032     * <a href="http://www.javaspecialists.co.za/archive/newsletter.do?issue=113">
033     * The JavaSpecialists newsletter</a>.
034     * 
035     * @param <K> 
036     * @param <E> 
037     * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
038     * @version $Rev$, $Date$
039     */
040    public class ReverseEnumMap<K, E extends Enum<E> & EnumConverter<K>>
041    {
042        private Map<K, E> reverseMap = new HashMap<K, E>();
043    
044    
045        /**
046         * Creates a new instance of ReverseEnumMap.
047         *
048         * @param enumType
049         */
050        public ReverseEnumMap( Class<E> enumType )
051        {
052            for ( E e : enumType.getEnumConstants() )
053            {
054                reverseMap.put( e.convert(), e );
055            }
056        }
057    
058    
059        /**
060         * Return the enum given an ordinal value.
061         *
062         * @param value
063         * @return The enum.
064         */
065        public E get( K value )
066        {
067            E e = reverseMap.get( value );
068            if ( e == null )
069            {
070                throw new IllegalArgumentException( I18n.err( I18n.ERR_650, value ) );
071            }
072            return e;
073        }
074    }