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 25 An always-empty Enumerator. 26 27 @author Anders Kristensen 28 @since version 1.0 29 */ 30 public class NullEnumeration implements Enumeration { 31 private static final NullEnumeration instance = new NullEnumeration(); 32 33 private 34 NullEnumeration() { 35 } 36 37 public static NullEnumeration getInstance() { 38 return instance; 39 } 40 41 public 42 boolean hasMoreElements() { 43 return false; 44 } 45 46 public 47 Object nextElement() { 48 throw new NoSuchElementException(); 49 } 50 }