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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  }