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

/*   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
 *   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="">Fredrik Westermarck</a>
 * @author Nikolay Metchev
 * @author Matthew Hawthorne
 * @author Tim O'Brien
 * @author Pete Gieser
 * @author Gary Gregory
 * @author <a href="">Ashwin S</a>
 * @author Maarten Coene
 * @since 2.0
 * @version $Id: 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);

7.9.1.Determining If an Object Is an Array
7.9.2.Demonstrates the use of the Array class
7.9.3.Create array with Array.newInstance
7.9.4.Is field an array
7.9.5.Create integer array with Array.newInstance
7.9.6.Use Array.setInt to fill an array
7.9.7.Use Array.setShort and Array.setLong
7.9.8.Getting the Length and Dimensions of an Array Object
7.9.9.Getting the Component Type of an Array Object
7.9.10.Array reflection and two dimensional array
7.9.11.class name for double and float array
7.9.12.Returns the length of the specified array, can deal with Object arrays and with primitive arrays.