Check out example codes for "how to create an array with unique values". It will help you in understanding the concepts better.

Code Example 1

import java.util.Random;

public class GenRandArray {
    //Recommend reseeding within methods
    static Random rand = new Random();

    public static void fillInt( int[] fillArray ) {
        //seeds the random for a new random each method call
        for(int i = 0; i < fillArray.length; i++)
            fillArray[i]= rand.nextInt();
          	/* for loop to check to make sure that none of the previous
               numbers added are the same as the one just added. */
            for (int j = 0; j < i; j++)
              	/* if so we need to redo the last random number by
              	   moving i back one index to be re-set */
                if (fillArray[i] == fillArray[j])

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