Something

window	
	contentPane.setLayout(new BorderLayout());
		contentPane.add(uhr2Dmain, BorderLayout.WEST);
		uhr2Dmain.setSize(30, 30);
		contentPane.add(panEingabe, BorderLayout.CENTER);
		contentPane.add(panButtons, BorderLayout.SOUTH);
		contentPane.add(listDaten, BorderLayout.EAST);

2D class

public class Java2D extends JComponent {
	
	Rectangle2D.Float rand = new Rectangle2D.Float(20, 20, 30 , 30);

    
	public Java2D (){
		System.out.println("test");
		
	}
	public void paint (Graphics g){
		Graphics2D g2 = (Graphics2D) g;
		g2.setStroke(new BasicStroke(1));
		g2.draw(rand);
		}
}