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 }