    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.log4j.helpers;
    019
    020import java.util.Enumeration;
    021import java.util.NoSuchElementException;
    022
    023/**
    024 * An always-empty Enumerator.
    025 *
    026 * @author Anders Kristensen
    027 * @since version 1.0
    028 */
    029@SuppressWarnings("rawtypes")
    030public class NullEnumeration implements Enumeration {
    031    private static final NullEnumeration instance = new NullEnumeration();
    032
    033    private NullEnumeration() {
    034    }
    035
    036    public static NullEnumeration getInstance() {
    037        return instance;
    038    }
    039
    040    public boolean hasMoreElements() {
    041        return false;
    042    }
    043
    044    public Object nextElement() {
    045        throw new NoSuchElementException();
    046    }
    047}