Main.java Source code

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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;

/**
 * <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>Inserts the specified element at the specified position in the array. 
     * Shifts the element currently at that position (if any) and any subsequent
     * elements to the right (adds one to their indices).</p>
     *
     * <p>This method returns a new array with the same elements of the input
     * array plus the given element on the specified position. The component 
     * type of the returned array is always 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([1.1], 0, 2.2)              = [2.2, 1.1]
     * ArrayUtils.add([2.3, 6.4], 2, 10.5)        = [2.3, 6.4, 10.5]
     * ArrayUtils.add([2.6, 6.7], 0, -4.8)        = [-4.8, 2.6, 6.7]
     * ArrayUtils.add([2.9, 6.0, 0.3], 2, 1.0)    = [2.9, 6.0, 1.0, 0.3]
     * </pre>
     * 
     * @param array  the array to add the element to, may be <code>null</code>
     * @param index  the position of the new object
     * @param element  the object to add
     * @return A new array containing the existing elements and the new element
     * @throws IndexOutOfBoundsException if the index is out of range 
     * (index < 0 || index > array.length).
     */
    public static double[] add(double[] array, int index, double element) {
        return (double[]) add(array, index, new Double(element), Double.TYPE);
    }

    /**
     * Underlying implementation of add(array, index, element) methods. 
     * The last parameter is the class, which may not equal element.getClass 
     * for primitives.
     *
     * @param array  the array to add the element to, may be <code>null</code>
     * @param index  the position of the new object
     * @param element  the object to add
     * @param clss the type of the element being added
     * @return A new array containing the existing elements and the new element
     */
    private static Object add(Object array, int index, Object element, Class clss) {
        if (array == null) {
            if (index != 0) {
                throw new IndexOutOfBoundsException("Index: " + index + ", Length: 0");
            }
            Object joinedArray = Array.newInstance(clss, 1);
            Array.set(joinedArray, 0, element);
            return joinedArray;
        }
        int length = Array.getLength(array);
        if (index > length || index < 0) {
            throw new IndexOutOfBoundsException("Index: " + index + ", Length: " + length);
        }
        Object result = Array.newInstance(clss, length + 1);
        System.arraycopy(array, 0, result, 0, index);
        Array.set(result, index, element);
        if (index < length) {
            System.arraycopy(array, index, result, index + 1, length - index);
        }
        return result;
    }

}