import java.awt.*;
import javax.swing.*;

// A panel that draws two rectangles on its surface.
public class RectPanel extends JPanel {
    public void paintComponent(Graphics g) {
        super.paintComponent(g);  // call JPanel's version
        g.setColor(Color.RED);
        g.fillRect(20, 40, 70, 30);
        g.setColor(Color.BLUE);
        g.fillRect(60, 10, 20, 80);
    }
}