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    package org.apache.directory.shared.ldap.util;
021    
022    
023    import java.util.NoSuchElementException;
024    
025    import javax.naming.NamingException;
026    import javax.naming.NamingEnumeration;
027    
028    
029    /**
030     * An empty NamingEnumeration without any values: meaning
031     * hasMore/hasMoreElements() always returns false, and next/nextElement() always
032     * throws a NoSuchElementException.
033     * 
034     * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
035     * @version $Revision: 574314 $
036     */
037    public class EmptyEnumeration<T> implements NamingEnumeration<T>
038    {
039    
040        /**
041         * @see javax.naming.NamingEnumeration#close()
042         */
043        public void close()
044        {
045        }
046    
047    
048        /**
049         * Always returns false.
050         * 
051         * @see javax.naming.NamingEnumeration#hasMore()
052         */
053        public boolean hasMore() throws NamingException
054        {
055            return false;
056        }
057    
058    
059        /**
060         * Always throws NoSuchElementException.
061         * 
062         * @see javax.naming.NamingEnumeration#next()
063         */
064        public T next() throws NamingException
065        {
066            throw new NoSuchElementException();
067        }
068    
069    
070        /**
071         * Always return false.
072         * 
073         * @see java.util.Enumeration#hasMoreElements()
074         */
075        public boolean hasMoreElements()
076        {
077            return false;
078        }
079    
080    
081        /**
082         * Always throws NoSuchElementException.
083         * 
084         * @see java.util.Enumeration#nextElement()
085         */
086        public T nextElement()
087        {
088            throw new NoSuchElementException();
089        }
090    
091    }