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 * * 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; /** * <p>Operations on arrays, primitive arrays (like <code>int[]</code>) and * primitive wrapper arrays (like <code>Integer[]</code>).</p> * * <p>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.</p> * * @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 { /** * <p>Adds all the elements of the given arrays into a new array.</p> * <p>The new array contains all of the element of <code>array1</code> followed * by all of the elements <code>array2</code>. When an array is returned, it is always * a new array.</p> * * <pre> * ArrayUtils.addAll(null, null) = null * ArrayUtils.addAll(array1, null) = cloned copy of array1 * ArrayUtils.addAll(null, array2) = cloned copy of array2 * ArrayUtils.addAll([], []) = [] * ArrayUtils.addAll([null], [null]) = [null, null] * ArrayUtils.addAll(["a", "b", "c"], ["1", "2", "3"]) = ["a", "b", "c", "1", "2", "3"] * </pre> * * @param array1 the first array whose elements are added to the new array, may be <code>null</code> * @param array2 the second array whose elements are added to the new array, may be <code>null</code> * @return The new array, <code>null</code> if <code>null</code> array inputs. * The type of the new array is the type of the first array. * @since 2.1 */ public static Object[] addAll(Object[] array1, Object[] array2) { if (array1 == null) { return clone(array2); } else if (array2 == null) { return clone(array1); } Object[] joinedArray = (Object[]) Array.newInstance(array1.getClass().getComponentType(), array1.length + array2.length); System.arraycopy(array1, 0, joinedArray, 0, array1.length); System.arraycopy(array2, 0, joinedArray, array1.length, array2.length); return joinedArray; } /** * <p>Shallow clones an array returning a typecast result and handling * <code>null</code>.</p> * * <p>The objects in the array are not cloned, thus there is no special * handling for multi-dimensional arrays.</p> * * <p>This method returns <code>null</code> for a <code>null</code> input array.</p> * * @param array the array to shallow clone, may be <code>null</code> * @return the cloned array, <code>null</code> if <code>null</code> input */ public static Object[] clone(Object[] array) { if (array == null) { return null; } return (Object[]) array.clone(); } }