1  /**

  2     This program computes an estimate of pi by simulating dart throws onto a square.

  3  */

  4  public class MonteCarlo

  5  {

  6     public static void main(String[] args)

  7     {  

  8        final int TRIES = 10000;

  9  

 10        int hits = 0;

 11        for (int i = 1; i <= TRIES; i++)

 12        {  

 13           // Generate two random numbers between -1 and 1

 14  

 15           double r = Math.random();

 16           double x = -1 + 2 * r; 

 17           r = Math.random();

 18           double y = -1 + 2 * r;         

 19  

 20           // Check whether the point lies in the unit circle

 21  

 22           if (x * x + y * y <= 1) { hits++; }

 23        }

 24  

 25        /*

 26           The ratio hits / tries is approximately the same as the ratio 

 27           circle area / square area = pi / 4

 28        */        

 29  

 30        double piEstimate = 4.0 * hits / TRIES;

 31        System.out.println("Estimate for pi: " + piEstimate);

 32     }

 33  }