import java.awt.Canvas;

import java.awt.Graphics;

import javax.swing.JFrame;

public class Drawing extends Canvas {

public static void main(String[] args) {

JFrame frame = new JFrame("My Drawing");

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

Canvas drawing = new Drawing();

drawing.setSize(400, 400);

frame.add(drawing);

frame.pack();

frame.setVisible(true);

}

public void paint(Graphics g) {

g.fillOval(100, 100, 200, 200);

}

}