Returns the length of the specified array, can deal with Object arrays and with primitive arrays. : Array « Reflection « Java Tutorial

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/*   Copyright 2004 The Apache Software Foundation
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *  limitations under the License.
 */


import java.lang.reflect.Array;


/**
 * Operations on arrays, primitive arrays (like <code>int[]</code>) and
 * primitive wrapper arrays (like <code>Integer[]</code>).
 * 
 * This class tries to handle <code>null</code> input gracefully.
 * An exception will not be thrown for a <code>null</code>
 * array input. However, an Object array that contains a <code>null</code>
 * element may throw an exception. Each method documents its behaviour.
 *
 * @author Stephen Colebourne
 * @author Moritz Petersen
 * @author <a href="mailto:fredrik@westermarck.com">Fredrik Westermarck</a>
 * @author Nikolay Metchev
 * @author Matthew Hawthorne
 * @author Tim O'Brien
 * @author Pete Gieser
 * @author Gary Gregory
 * @author <a href="mailto:equinus100@hotmail.com">Ashwin S</a>
 * @author Maarten Coene
 * @since 2.0
 * @version $Id: ArrayUtils.java 632503 2008-03-01 00:21:52Z ggregory $
 */
public class Main {
  //-----------------------------------------------------------------------
  /**
   * Returns the length of the specified array.
   * This method can deal with <code>Object</code> arrays and with primitive arrays.
   *
   * If the input array is <code>null</code>, <code>0</code> is returned.
   *
   * <pre>
   * ArrayUtils.getLength(null)            = 0
   * ArrayUtils.getLength([])              = 0
   * ArrayUtils.getLength([null])          = 1
   * ArrayUtils.getLength([true, false])   = 2
   * ArrayUtils.getLength([1, 2, 3])       = 3
   * ArrayUtils.getLength(["a", "b", "c"]) = 3
   * </pre>
   *
   * @param array  the array to retrieve the length from, may be null
   * @return The length of the array, or <code>0</code> if the array is <code>null</code>
   * @throws IllegalArgumentException if the object arguement is not an array.
   * @since 2.1
   */
  public static int getLength(Object array) {
      if (array == null) {
          return 0;
      }
      return Array.getLength(array);
  }
}