import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ComponentEvent;

public class PaintTest extends JFrame{
    private JPanel panel1;
    private JButton button1;
    private JRadioButton radioButton1;
    private JRadioButton radioButton2;


   public PaintTest() {
       super("Hello World");


       setContentPane(panel1);

       pack();
       setDefaultLookAndFeelDecorated(false);
       setMinimumSize(new Dimension(300,300) );
       setResizable(true);
       setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       setVisible(true);

       button1.addActionListener(new ActionListener() {
           @Override
           public void actionPerformed(ActionEvent e) {
               update(panel1.getGraphics());
           }

       });


   }
    @Override
    public void update(Graphics g){
        paintComponent(g);
    }

    protected void paintComponent(Graphics g)
    {
        super.paintComponents(g);
        Graphics2D g2d = (Graphics2D)g;

        g2d.setColor(Color.yellow);
        g2d.fillRect(30, 30, 100, 100);
        g2d.drawLine(0,0, 200,200);
    }
}