// This code example is created for educational purpose
// by Thorsten Thormaehlen (contact: www.thormae.de).
// It is distributed without any warranty.

import java.awt.*;
import java.awt.geom.*;
import java.awt.geom.Line2D;

import javax.swing.*;

class MyGui extends JFrame {
  public void createGUI() {
    setTitle("HelloGUI");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setSize(320, 240);
    setVisible(true);
  }
  @Override
  public void paint(Graphics g) {
    super.paint(g);
    Graphics2D g2d = (Graphics2D) g; // cast to Graphics2D
    Line2D.Double line = new Line2D.Double(20.0, 50.0, 50.0, 200.0);
    g2d.draw(line);
    Rectangle2D.Double rect = new Rectangle2D.Double(100.0, 50.0, 60.0, 80.0);
    g2d.draw(rect); // also try g2d.fill(rect);
    Ellipse2D.Double circle = new Ellipse2D.Double(200.0, 100.0, 80.0, 80.0);
    g2d.draw(circle); // also try g2d.fill(circle); 
  }
}

public class LineRectCircle {
  public static void main(String[] args) {
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        MyGui myGUI = new MyGui();
        myGUI.createGUI();
      }
    });
  }
}