Returns an int[] containing elements shared between the two arrays - Java Collection Framework

Java examples for Collection Framework:Array Contain

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Description

Returns an int[] containing elements shared between the two arrays

Demo Code

/* Copyright (c) 2001-2010, The HSQL Development Group
 * All rights reserved.//  w ww. j av a  2  s . c om
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 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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//package com.java2s;

public class Main {
    public static void main(String[] argv) throws Exception {
        int[] arra = new int[] { 34, 35, 36, 37, 37, 37, 67, 68, 69 };
        int[] arrb = new int[] { 34, 35, 36, 37, 37, 37, 67, 68, 69 };
        System.out.println(java.util.Arrays.toString(commonElements(arra,
                arrb)));
    }

    /**
     * Returns an int[] containing elements shared between the two arrays
     * arra and arrb. The arrays contain sets (no value is repeated).
     *
     * Used to find the overlap between two arrays of column indexes.
     * Ordering of the result arrays will be the same as in array
     * a. The method assumes that each index is only listed
     * once in the two input arrays.
     * <p>
     * e.g.
     * </p>
     * <code>
     * <table width="90%" bgcolor="lightblue">
     * <tr><td colspane="3">The arrays</td></tr>
     * <tr><td>int []arra</td><td>=</td><td>{2,11,5,8}</td></tr>
     * <tr><td>int []arrb</td><td>=</td><td>{20,8,10,11,28,12}</td></tr>
     * <tr><td colspane="3">will result in:</td></tr>
     * <tr><td>int []arrc</td><td>=</td><td>{11,8}</td></tr>
     * </table>
     *
     * @param arra int[]; first column indexes
     * @param arrb int[]; second column indexes
     * @return int[] common indexes or <code>null</code> if there is no overlap.
     */
    public static int[] commonElements(int[] arra, int[] arrb) {

        int[] c = null;
        int n = countCommonElements(arra, arrb);

        if (n > 0) {
            c = new int[n];

            int k = 0;

            for (int i = 0; i < arra.length; i++) {
                for (int j = 0; j < arrb.length; j++) {
                    if (arra[i] == arrb[j]) {
                        c[k++] = arra[i];
                    }
                }
            }
        }

        return c;
    }

    /**
     * Returns the number of elements shared between the two arrays containing
     * sets.<p>
     *
     * Return the number of elements shared by two column index arrays.
     * This method assumes that each of these arrays contains a set (each
     * element index is listed only once in each index array). Otherwise the
     * returned number will NOT represent the number of unique column indexes
     * shared by both index array.
     *
     * @param arra int[]; first array of column indexes.
     *
     * @param arrb int[]; second array of column indexes
     *
     * @return int; number of elements shared by <code>a</code> and <code>b</code>
     */
    public static int countCommonElements(int[] arra, int[] arrb) {

        int k = 0;

        for (int i = 0; i < arra.length; i++) {
            for (int j = 0; j < arrb.length; j++) {
                if (arra[i] == arrb[j]) {
                    k++;
                }
            }
        }

        return k;
    }
}

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