Java tutorial
//package com.java2s; /* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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; public class Main { /** * 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}. * @param newArrayComponentType If {@code array} is {@code null}, 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(final Object array, final Class<?> newArrayComponentType) { if (array != null) { final int arrayLength = Array.getLength(array); final Object newArray = Array.newInstance(array.getClass().getComponentType(), arrayLength + 1); System.arraycopy(array, 0, newArray, 0, arrayLength); return newArray; } return Array.newInstance(newArrayComponentType, 1); } /** * <p>Returns the length of the specified array. * This method can deal with {@code Object} arrays and with primitive arrays.</p> * * <p>If the input array is {@code null}, {@code 0} is returned.</p> * * <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} if the array is {@code null} * @throws IllegalArgumentException if the object argument is not an array. * @since 2.1 */ public static int getLength(final Object array) { if (array == null) { return 0; } return Array.getLength(array); } }