NullEnumeration


1   /*
2    * Copyright 1999-2005 The Apache Software Foundation.
3    * 
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    * 
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    * 
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.apache.log4j.helpers;
18  
19  import java.util.Enumeration  ;
20  import java.util.NoSuchElementException  ;
21  
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
33    NullEnumeration() {
34    }
35    
36    public static NullEnumeration getInstance() {
37      return instance;
38    }
39    
40    public
41    boolean hasMoreElements() {
42      return false;
43    }
44    
45    public
46    Object   nextElement() {
47      throw new NoSuchElementException  ();
48    }
49  }
50

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