UnmodifiableOrderedMapIterator


1   /*
2    *  Copyright 1999-2004 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  package org.apache.commons.collections.iterators;
17  
18  import org.apache.commons.collections.OrderedMapIterator;
19  import org.apache.commons.collections.Unmodifiable;
20  
21  /** 
22   * Decorates an ordered map iterator such that it cannot be modified.
23   *
24   * @since Commons Collections 3.0
25   * @version $Revision: 1.6 $ $Date: 2004/02/18 00:59:50 $
26   * 
27   * @author Stephen Colebourne
28   */
29  public final class UnmodifiableOrderedMapIterator implements OrderedMapIterator, Unmodifiable {
30  
31      /** The iterator being decorated */
32      private OrderedMapIterator iterator;
33  
34      //-----------------------------------------------------------------------
35      /**
36       * Decorates the specified iterator such that it cannot be modified.
37       *
38       * @param iterator  the iterator to decorate
39       * @throws IllegalArgumentException if the iterator is null
40       */
41      public static OrderedMapIterator decorate(OrderedMapIterator iterator) {
42          if (iterator == null) {
43              throw new IllegalArgumentException  ("OrderedMapIterator must not be null");
44          }
45          if (iterator instanceof Unmodifiable) {
46              return iterator;
47          }
48          return new UnmodifiableOrderedMapIterator(iterator);
49      }
50      
51      //-----------------------------------------------------------------------
52      /**
53       * Constructor.
54       *
55       * @param iterator  the iterator to decorate
56       */
57      private UnmodifiableOrderedMapIterator(OrderedMapIterator iterator) {
58          super();
59          this.iterator = iterator;
60      }
61  
62      //-----------------------------------------------------------------------
63      public boolean hasNext() {
64          return iterator.hasNext();
65      }
66  
67      public Object   next() {
68          return iterator.next();
69      }
70  
71      public boolean hasPrevious() {
72          return iterator.hasPrevious();
73      }
74  
75      public Object   previous() {
76          return iterator.previous();
77      }
78  
79      public Object   getKey() {
80          return iterator.getKey();
81      }
82  
83      public Object   getValue() {
84          return iterator.getValue();
85      }
86  
87      public Object   setValue(Object   value) {
88          throw new UnsupportedOperationException  ("setValue() is not supported");
89      }
90  
91      public void remove() {
92          throw new UnsupportedOperationException  ("remove() is not supported");
93      }
94  
95  }
96
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