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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the 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 io.netty.channel.group;
17  
18  import java.util.Iterator;
19  import java.util.NoSuchElementException;
20  
21  /**
22   */
23  final class CombinedIterator<E> implements Iterator<E> {
24  
25      private final Iterator<E> i1;
26      private final Iterator<E> i2;
27      private Iterator<E> currentIterator;
28  
29      CombinedIterator(Iterator<E> i1, Iterator<E> i2) {
30          if (i1 == null) {
31              throw new NullPointerException("i1");
32          }
33          if (i2 == null) {
34              throw new NullPointerException("i2");
35          }
36          this.i1 = i1;
37          this.i2 = i2;
38          currentIterator = i1;
39      }
40  
41      @Override
42      public boolean hasNext() {
43          for (;;) {
44              if (currentIterator.hasNext()) {
45                  return true;
46              }
47  
48              if (currentIterator == i1) {
49                  currentIterator = i2;
50              } else {
51                  return false;
52              }
53          }
54      }
55  
56      @Override
57      public E next() {
58          for (;;) {
59              try {
60                  return currentIterator.next();
61              } catch (NoSuchElementException e) {
62                  if (currentIterator == i1) {
63                      currentIterator = i2;
64                  } else {
65                      throw e;
66                  }
67              }
68          }
69      }
70  
71      @Override
72      public void remove() {
73          currentIterator.remove();
74      }
75  
76  }