public class Display{
	JFrame frame;	
	JPanel contentPane;
	public Display()
	{
		frame = new JFrame("Painting example");	//initialize JFrame
		contentPane = new JPanel();
		contentPane.setBorder(BorderFactory.createEmptyBorder(20,20,20,20));
		contentPane.setLayout(new GridLayout(1,0));
		
		panel.setContentPane(contentPane);	// Add content pane to frame
		contentPane.add(new MyPanel());	//Add paint surface
	}
	public static void main(String[] args)
	{
		Display g1 = new Display();
	}
}
class MyPanel extends JPanel{
	public MyPanel() {
        	setBorder(BorderFactory.createLineBorder(Color.black));
    	}

    	public Dimension getPreferredSize() {
        	return new Dimension(250,200);
    	}

    	public void paintComponent(Graphics g) {
        	super.paintComponent(g);
// You can add paint objects here or implement double/triple buffering and access it from your main class(es)
       		g.setColor(Color.BLACK);
        	g.fillRect(0, 0, 1000, 1000);
        	g.setColor(Color.RED);
        	g.fillOval(100, 100, 10, 10);
    	}
}