find unique elements in array O(n) code example

Example 1: how to create an array with unique values

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
        rand.setSeed(System.currentTimeMillis());
		
        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])
                {
                    i--;
                }
            }
        }
    }
}

Example 2: get an array with unique values

function onlyUnique(value, index, self) {
  return self.indexOf(value) === index;
}

// usage example:
var a = ['a', 1, 'a', 2, '1'];
var unique = a.filter(onlyUnique);

console.log(unique); // ['a', 1, 2, '1']