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 @SuppressWarnings("rawtypes")
30 public class NullEnumeration implements Enumeration {
31 private static final NullEnumeration instance = new NullEnumeration();
32
33 private NullEnumeration() {
34 }
35
36 public static NullEnumeration getInstance() {
37 return instance;
38 }
39
40 public boolean hasMoreElements() {
41 return false;
42 }
43
44 public Object nextElement() {
45 throw new NoSuchElementException();
46 }
47 }