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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *   http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package org.apache.myfaces.shared.util;
20  
21  import java.util.Iterator;
22  import java.util.NoSuchElementException;
23  
24  /**
25   * Iterator without elements
26   *
27   * @author Anton Koinov (latest modification by $Author: bommel $)
28   * @version $Revision: 1187701 $ $Date: 2011-10-22 07:21:54 -0500 (Sat, 22 Oct 2011) $
29   */
30  public final class NullIterator<T> implements Iterator<T>
31  {
32      //~ Static fields/initializers -----------------------------------------------------------------
33  
34      private static final NullIterator<?> INSTANCE = new NullIterator<Object>();
35  
36      //~ Methods ------------------------------------------------------------------------------------
37  
38      @SuppressWarnings("unchecked")
39      public static final <T> Iterator<T> instance()
40      {
41          return (Iterator<T>) INSTANCE;
42      }
43  
44      public boolean hasNext()
45      {
46          return false;
47      }
48  
49      public T next()
50      {
51          throw new NoSuchElementException();
52      }
53  
54      public void remove()
55      {
56          throw new UnsupportedOperationException(this.getClass().getName() + " UnsupportedOperationException");
57      }
58  }