Time difference between Parallel and Sequential Sort (using java 8)

import java.io.*;

import java.util.*;

import java.util.Arrays;

public class Parallel_Sort

{

public static void main(String[] args)

{

// Create a list and populate it with random numbers

List<Integer> list = new ArrayList();

Random r = new Random();

for (int x = 0; x < 500000; x++)

{

list.add(r.nextInt(10000));

}

// Create two arrays for sorting.

Integer[] array1 = new Integer[list.size()];

Integer[] array2 = new Integer[list.size()];

array1 = list.toArray(array1);

array2 = list.toArray(array2);

// sort array

long start = System.currentTimeMillis();

Arrays.sort(array1);

long end = System.currentTimeMillis();

double ss = (double)(end - start)/1000;

System.out.println("Sort Time(Sequential): " + ss);

// sort array using parallel sort

start = System.currentTimeMillis();

Arrays.parallelSort(array2);

end = System.currentTimeMillis();

double ps = (double)(end - start)/1000;

System.out.println("Parallel Sort Time(Parallel): " + ps);

System.out.println("Time Difference is: " + (double)(ss-ps));

}

}

OUTPUT:

C:\Users\java>java Parallel_Sort

Sort Time(Sequential): 0.141

Parallel Sort Time(Parallel): 0.078

Time Difference is: 0.06299999999999999