Furt to mas pomale.

public class Test {

    public static void main(String[] args) {
            long timeBefore = System.nanoTime();

            double i = Math.pow(10, 9);
            long retyped = 0;

            long timeAfter = System.nanoTime();
            long time = (timeAfter - timeBefore) / 1000000;
            System.out.println(time + " ms");
        }
}