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>Copies the given array and adds the given element at the end of the new array.</p> * * <p>The new array contains the same elements of the input * array plus the given element in the last position. The component type of * the new array is the same as that of the input array.</p> * * <p>If the input array is <code>null</code>, a new one element array is returned * whose component type is the same as the element.</p> * * <pre> * ArrayUtils.add(null, 0) = [0] * ArrayUtils.add([1], 0) = [1, 0] * ArrayUtils.add([1, 0], 1) = [1, 0, 1] * </pre> * * @param array the array to copy and add the element to, may be <code>null</code> * @param element the object to add at the last index of the new array * @return A new array containing the existing elements plus the new element * @since 2.1 */ public static long[] add(long[] array, long element) { long[] newArray = (long[]) copyArrayGrow1(array, Long.TYPE); newArray[newArray.length - 1] = element; return newArray; } /** * Returns a copy of the given array of size 1 greater than the argument. * The last value of the array is left to the default value. * * @param array The array to copy, must not be <code>null</code>. * @param newArrayComponentType If <code>array</code> is <code>null</code>, create a * size 1 array of this type. * @return A new copy of the array of size 1 greater than the input. */ private static Object copyArrayGrow1(Object array, Class newArrayComponentType) { if (array != null) { int arrayLength = Array.getLength(array); Object newArray = Array.newInstance(array.getClass().getComponentType(), arrayLength + 1); System.arraycopy(array, 0, newArray, 0, arrayLength); return newArray; } return Array.newInstance(newArrayComponentType, 1); } }