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");
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);
}
}