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1   /*
2    * Copyright 2009 Red Hat, Inc.
3    *
4    * Red Hat licenses this file to you under the Apache License, version 2.0
5    * (the "License"); you may not use this file except in compliance with the
6    * License.  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, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package org.jboss.netty.channel.group;
17  
18  import java.util.Iterator;
19  import java.util.NoSuchElementException;
20  
21  /**
22   * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
23   * @author <a href="http://gleamynode.net/">Trustin Lee</a>
24   * @version $Rev: 2080 $, $Date: 2010-01-26 18:04:19 +0900 (Tue, 26 Jan 2010) $
25   */
26  final class CombinedIterator<E> implements Iterator<E> {
27  
28      private final Iterator<E> i1;
29      private final Iterator<E> i2;
30      private Iterator<E> currentIterator;
31  
32      CombinedIterator(Iterator<E> i1, Iterator<E> i2) {
33          if (i1 == null) {
34              throw new NullPointerException("i1");
35          }
36          if (i2 == null) {
37              throw new NullPointerException("i2");
38          }
39          this.i1 = i1;
40          this.i2 = i2;
41          currentIterator = i1;
42      }
43  
44      public boolean hasNext() {
45          boolean hasNext = currentIterator.hasNext();
46          if (hasNext) {
47              return true;
48          }
49  
50          if (currentIterator == i1) {
51              currentIterator = i2;
52              return hasNext();
53          } else {
54              return false;
55          }
56      }
57  
58      public E next() {
59          try {
60              E e = currentIterator.next();
61              return e;
62          } catch (NoSuchElementException e) {
63              if (currentIterator == i1) {
64                  currentIterator = i2;
65                  return next();
66              } else {
67                  throw e;
68              }
69          }
70      }
71  
72      public void remove() {
73          currentIterator.remove();
74      }
75  
76  }