Java tutorial
import java.awt.Color; import java.awt.Graphics; import javax.swing.JFrame; import javax.swing.JPanel; public class Main extends JPanel { public Main() { } public void paintComponent(Graphics g) { int width = getWidth(); int height = getHeight(); g.setColor(Color.black); g.drawOval(0, 0, width, height); } public static void main(String args[]) { JFrame frame = new JFrame("Oval Sample"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.add(new Main()); frame.setSize(300, 200); frame.setVisible(true); } }