Java tutorial
import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Rectangle; import javax.swing.JFrame; import javax.swing.JPanel; public class Main extends JPanel { public void paint(Graphics g) { Graphics2D g2 = (Graphics2D) g; Rectangle r = new Rectangle(10, 10, 50, 40); r.add(new Rectangle(40, 40, 100, 100)); g2.fill(r); } public static void main(String[] args) { JFrame frame = new JFrame(); frame.getContentPane().add(new Main()); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(200, 200); frame.setVisible(true); } }