1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package org.apache.log4j.helpers; 19 20 import java.util.Enumeration; 21 import java.util.NoSuchElementException; 22 23 /** 24 * An always-empty Enumerator. 25 * 26 * @author Anders Kristensen 27 * @since version 1.0 28 */ 29 public class NullEnumeration implements Enumeration { 30 private static final NullEnumeration instance = new NullEnumeration(); 31 32 private NullEnumeration() { 33 } 34 35 public static NullEnumeration getInstance() { 36 return instance; 37 } 38 39 public boolean hasMoreElements() { 40 return false; 41 } 42 43 public Object nextElement() { 44 throw new NoSuchElementException(); 45 } 46 }