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 */
020package org.apache.directory.api.util;
021
022
023import java.util.NoSuchElementException;
024
025import javax.naming.NamingException;
026import 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 * @param <T> The element in the enumeration
035 * 
036 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
037 */
038public class EmptyEnumeration<T> implements NamingEnumeration<T>
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}