import java.util.Arrays;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

/**

 * Java program to remove duplicates from this array. You don't

 * need to physically delete duplicate elements, replacing with null, or

 * empty or default value is ok.

 *

 * @author http://javarevisited.blogspot.com

 */

public class TechnicalInterviewTest {

    private static final Logger logger = LoggerFactory.getLogger(TechnicalInterviewTest.class);

    public static void main(String args[]) {

        int[][] test = new int[][]{

            {1, 1, 2, 2, 3, 4, 5},

            {1, 1, 1, 1, 1, 1, 1},

            {1, 2, 3, 4, 5, 6, 7},

            {1, 2, 1, 1, 1, 1, 1},};

        for (int[] input : test) {

            System.out.println("Array with Duplicates       : " + Arrays.toString(input));

            System.out.println("After removing duplicates   : " + Arrays.toString(removeDuplicates(input)));

        }

    }

    /*

     * Method to remove duplicates from array in Java, without using

     * Collection classes e.g. Set or ArrayList. Algorithm for this

     * method is simple, it first sort the array and then compare adjacent

     * objects, leaving out duplicates, which is already in the result.

     */

    public static int[] removeDuplicates(int[] numbersWithDuplicates) {

        // Sorting array to bring duplicates together      

        Arrays.sort(numbersWithDuplicates);     

        int[] result = new int[numbersWithDuplicates.length];

        int previous = numbersWithDuplicates[0];

        result[0] = previous;

        for (int i = 1; i < numbersWithDuplicates.length; i++) {

            int ch = numbersWithDuplicates[i];

            if (previous != ch) {

                result[i] = ch;

            }

            previous = ch;

        }

        return result;

    }

}

Array with Duplicates       : [1, 1, 2, 2, 3, 4, 5]

After removing duplicates   : [1, 0, 2, 0, 3, 4, 5]

Array with Duplicates       : [1, 1, 1, 1, 1, 1, 1]

After removing duplicates   : [1, 0, 0, 0, 0, 0, 0]

Array with Duplicates       : [1, 2, 3, 4, 5, 6, 7]

After removing duplicates   : [1, 2, 3, 4, 5, 6, 7]

Array with Duplicates       : [1, 2, 1, 1, 1, 1, 1]

After removing duplicates   : [1, 0, 0, 0, 0, 0, 2]