import javax.swing.*;

import java.awt.*;
import java.awt.event.*;

public class Main extends JLayeredPane {
    static JFrame frame;
    static Main main;
    static Dimension screenSize;
    public Main() {
        JPanel backPanel = new BackPanel();
        JPanel frontPanel = new FrontPanel();
        add(backPanel, new Integer(7));
        add(frontPanel, new Integer(8));

        new Thread(() -> {
            while (true){
                repaint();
            }
        }).start();

    }

    public static void main(String[] args) {
        screenSize = Toolkit.getDefaultToolkit().getScreenSize();

        frame = new JFrame("Game"); // Just use the constructor

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        main = new Main();
        frame.add(main, BorderLayout.CENTER);

        frame.pack();
        frame.setSize(screenSize);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);

    }
    public class BackPanel extends JPanel{
        public boolean drawn = false;
        public BackPanel(){
            setVisible(true);
            setOpaque(false);
            setSize(screenSize);
            JLabel test1 = new JLabel("Test1");
            JLabel test2 = new JLabel("Test2");
            add(test1);
            add(test2);
        }
        @Override
        public void paintComponent(Graphics g){
            super.paintComponent(g);
            drawOnce(g);
        }
        public void drawOnce(Graphics g){
            if (!drawn){
                g.setColor(Color.red);
                g.fillRect(0, 0, screenSize.width, 200);
                drawn=true;
            }

        }
    }
    public class FrontPanel extends JPanel{

        public FrontPanel(){
            setVisible(true);
            setOpaque(false);
            setSize(screenSize);
            JLabel test = new JLabel("Test");
            add(test);
        }
        @Override
        public void paintComponent(Graphics g){
            super.paintComponent(g);
            g.setColor(Color.blue);
            g.fillRect(0+screenSize.width/2, 0, screenSize.width/4, 300);
        }
    }
}

public void drawOnce(Graphics g){
       if (!drawn){
            g.setColor(Color.red);
            g.fillRect(0, 0, screenSize.width, 200);
            drawn=true;
            a++;
            System.out.println("BackPanel : "+a);
        }
        }


    public void paintComponent(Graphics g){
        super.paintComponent(g);
        g.setColor(Color.blue);
        g.fillRect(0+screenSize.width/2, 0, screenSize.width/4, 300);
        a++;
        System.out.println("FrontPanel : "+a);
    }