Class Main

import java.awt.Color;
import javax.swing.JFrame;

public class Main extends Thread {
        private static Kotak shapes2JPanel;
    public static void main(String[] args) {
        JFrame frame = new JFrame( "Drawing 2D Shapes" );
      frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );

      shapes2JPanel = new Kotak();
      frame.add( shapes2JPanel );
      frame.setBackground( Color.WHITE );
      frame.setSize( 400, 400 );
      frame.setVisible( true );
      Main m=new Main();
      m.start();
   }

    @Override
    public void run(){
        while (true){
            try{
                Main.sleep(100);
            }
            catch(InterruptedException ie){break;}
            shapes2JPanel.repaint();
        }
    }
}