Java random numbers not random?

Question

I was trying to explain the random number generator in Java to a friend when he kept getting the same numbers every time he ran the program. I created my own simpler version

Answer 1

Hope this helps..

Random r = new Random(System.currentTimeMillis());
double[] rand = new double[500];
for(int i=0;i<100;i++){
    rand[i] = r.nextDouble();
    //System.out.print(rand[i] + "\n");
}
//System.out.println();
return rand[randomInt];