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    1   /*
    2    * $Id: MakeIterator.java 471756 2006-11-06 15:01:43Z husted $
    3    *
    4    * Licensed to the Apache Software Foundation (ASF) under one
    5    * or more contributor license agreements.  See the NOTICE file
    6    * distributed with this work for additional information
    7    * regarding copyright ownership.  The ASF licenses this file
    8    * to you under the Apache License, Version 2.0 (the
    9    * "License"); you may not use this file except in compliance
    10   * with the License.  You may obtain a copy of the License at
    11   *
    12   *  http://www.apache.org/licenses/LICENSE-2.0
    13   *
    14   * Unless required by applicable law or agreed to in writing,
    15   * software distributed under the License is distributed on an
    16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    17   * KIND, either express or implied.  See the License for the
    18   * specific language governing permissions and limitations
    19   * under the License.
    20   */
    21  package org.apache.struts2.util;
    22
    23  import java.lang.reflect.Array;
    24  import java.util.ArrayList;
    25  import java.util.Collection;
    26  import java.util.Enumeration;
    27  import java.util.Iterator;
    28  import java.util.List;
    29  import java.util.Map;
    30
    31
    32  /***
    33   * MakeIterator.
    34   *
    35   */
    36  public class MakeIterator {
    37
    38      /***
    39       * Determine whether a given object can be made into an <code>Iterator</code>
    40       *
    41       * @param object the object to check
    42       * @return <code>true</code> if the object can be converted to an iterator and
    43       *         <code>false</code> otherwise
    44       */
    45      public static boolean isIterable(Object object) {
    46          if (object == null) {
    47              return false;
    48          }
    49
    50          if (object instanceof Map) {
    51              return true;
    52          } else if (object instanceof Collection) {
    53              return true;
    54          } else if (object.getClass().isArray()) {
    55              return true;
    56          } else if (object instanceof Enumeration) {
    57              return true;
    58          } else if (object instanceof Iterator) {
    59              return true;
    60          } else {
    61              return false;
    62          }
    63      }
    64
    65      public static Iterator convert(Object value) {
    66          Iterator iterator;
    67
    68          if (value instanceof Iterator) {
    69              return (Iterator) value;
    70          }
    71
    72          if (value instanceof Map) {
    73              value = ((Map) value).entrySet();
    74          }
    75
    76          if (value == null) {
    77              return null;
    78          }
    79
    80          if (value instanceof Collection) {
    81              iterator = ((Collection) value).iterator();
    82          } else if (value.getClass().isArray()) {
    83              //need ability to support primitives; therefore, cannot
    84              //use Object[] casting.
    85              ArrayList list = new ArrayList(Array.getLength(value));
    86
    87              for (int j = 0; j < Array.getLength(value); j++) {
    88                  list.add(Array.get(value, j));
    89              }
    90
    91              iterator = list.iterator();
    92          } else if (value instanceof Enumeration) {
    93              Enumeration enumeration = (Enumeration) value;
    94              ArrayList list = new ArrayList();
    95
    96              while (enumeration.hasMoreElements()) {
    97                  list.add(enumeration.nextElement());
    98              }
    99
    100             iterator = list.iterator();
    101         } else {
    102             List list = new ArrayList(1);
    103             list.add(value);
    104             iterator = list.iterator();
    105         }
    106
    107         return iterator;
    108     }
    109 }