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

class Cadre extends JFrame{

  public Cadre(){

    // operation de fermeture
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    // extraire les dimensions
    Toolkit kit=Toolkit.getDefaultToolkit();
    Dimension screenSize = kit.getScreenSize();

    // centrer l'image
    setSize(screenSize.width/2,screenSize.height/2);
    setLocation(screenSize.width/4,screenSize.height/4);
    
    // definir l'icone
    setTitle("Un titre");

    // ajouter le panneau au cadre
    add(new Panneau());
  }

  class Panneau extends JPanel
  {
    public Panneau()
    {
      setBackground(Color.white);
    }

    public void paintComponent(Graphics g){
      super.paintComponent(g);

      Graphics2D g2=(Graphics2D) g;
    
      // un rectangle
      double width = getWidth()/2;
      double height = getHeight()/2;
      double leftX = width/2;
      double topY = height/2;
      Rectangle2D rect = new Rectangle2D.Double(leftX,topY,width,height);
      g2.setPaint(new Color(0,128,128));
      g2.fill(rect);
      g2.setPaint(Color.black);
      g2.draw(rect);
    }
  }

  public static void main(String[] args){
    Cadre cadre = new Cadre();
    cadre.setVisible(true);
  }

}