Thread: How do I access frame class?

Program.java

import java.awt.Dimension;
import java.awt.Graphics;
import java.lang.*;
import javax.swing.*;
 
public class Program{
 
    public static void main(String[] args) {
 
		Main main = new Main();
		JFrame frame = new JFrame("Title");
		frame.add(main);
		frame.setVisible(true);
	        frame.pack();
		main.setup();
		main.update();
 
    }
 
}

Main.java

import java.awt.Graphics;
import java.util.concurrent.*;
import java.lang.*;
import javax.swing.*;
import java.awt.Dimension;
 
public class Main extends JPanel{
 
	public void setup(){
 
	}
 
	public void update(){
 
		while(true){
 
			try{
			TimeUnit.MILLISECONDS.sleep(16);
			frame.repaint();
			}catch(Exception E){}
		}
 
	}
 
	public void draw(Graphics g){
 
 
	}
 
	public Dimension getPreferredSize() {
 
        return new Dimension(500, 500);
 
    }
 
	//override stuff
	public void paintComponent(Graphics g) {
 
        super.paintComponent(g);
		draw(g);
 
    }
 
}

the problem is that I cannot access frame.repaint() in Main.java, how do I fix it? I prefer simple, beginner friendly looking code, not making AAA game.