Returns an array of the same size as the index Array and the class of the original Array which contains the elements of the original array selected by the corresponding indices. - Java Collection Framework

Java examples for Collection Framework:Array Contain

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Description

Returns an array of the same size as the index Array and the class of the original Array which contains the elements of the original array selected by the corresponding indices.

Demo Code

/**/*from www .j av  a 2 s .com*/
 * Copyright (c) 2010 Martin Geisse
 *
 * This file is distributed under the terms of the MIT license.
 */
import java.lang.reflect.Array;

public class Main{
    /**
     * Returns an array of the same size as the indexArray and the class of
     * the originalArray which contains the elements of the original array
     * selected by the corresponding indices.
     * @param <T> the static type of the original array
     * @param originalArray the original array form which objects are selected
     * @param indexArray the array of indices used to select elements of the
     * original array
     * @return Returns the selected elements.
     */
    public static <T> T[] selectByIndexArray(T[] originalArray,
            int[] indexArray) {
        Object[] untypedSelectedElements = (Object[]) Array.newInstance(
                originalArray.getClass().getComponentType(),
                indexArray.length);
        T[] selectedElements = ArrayUtil
                .<T> unsafeCastArray(untypedSelectedElements);
        for (int i = 0; i < indexArray.length; i++) {
            selectedElements[i] = originalArray[indexArray[i]];
        }
        return selectedElements;
    }
    /**
     * Returns an array of the same size as the indexArray and the class of
     * the originalArray which contains the elements of the original array
     * selected by the corresponding indices.
     * @param originalArray the original array form which objects are selected
     * @param indexArray the array of indices used to select elements of the
     * original array
     * @return Returns the selected elements.
     */
    public static int[] selectByIndexArray(int[] originalArray,
            int[] indexArray) {
        int[] selectedElements = (int[]) Array.newInstance(Integer.TYPE,
                indexArray.length);
        for (int i = 0; i < indexArray.length; i++) {
            selectedElements[i] = originalArray[indexArray[i]];
        }
        return selectedElements;
    }
    /**
     * Returns the argument, cast to type T[] in an unsafe way.
     * @param <T> the static element type of the array type to cast to
     * @param a the value to cast
     * @return Returns the argument, cast to type T[].
     */
    @SuppressWarnings("unchecked")
    private static <T> T[] unsafeCastArray(Object[] a) {
        return (T[]) a;
    }
}

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