import javax.swing.JPanel;
import java.awt.*;
import java.util.Random;

public class PiSquare extends JPanel
{
   public PiSquare()
   {
       setBackground(Color.black);
       setPreferredSize(new Dimension(300,300));
    }
    
    public void paintComponent(Graphics page)
    {
        super.paintComponent(page); // paints the background and sets the window size
     
        page.setColor(Color.white);
        
        Random point  = new Random();
        int i = 0;
        int n = 10000;     // set the number of random points
        int inside = 0;
        double x, y;       // Coordinates of a random point 

        do {
            i++;
            x = point.nextDouble()*2-1;    // Generate a random point
            y = point.nextDouble()*2-1;
            if (x*x + y*y <= 1) {
                inside++; // if inside the unit circle increment counter
                page.setColor(Color.white);
            }
            else 
                page.setColor(Color.blue);
            page.fillRect ((int)(x*100)+150, (int)(y*100)+150, 1, 1);
        } while (i < n);
        
        page.drawString ("Pi = " + String.valueOf (4*(float)inside/n), 50, 270);
   }

}