Java tutorial
/* * Output: * */ import java.awt.Graphics; import javax.swing.JFrame; import javax.swing.JPanel; public class MainClass extends JPanel { public void paint(Graphics g) { g.drawOval(25, 25, 120, 120); } public static void main(String[] args) { JFrame frame = new JFrame(); frame.getContentPane().add(new MainClass()); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(200, 200); frame.setVisible(true); } }