Help me draw a flowgraph for this code $/*$

package com.mtala$3$t$.$snake$2$d;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

import java.awt.Graphics$2$D;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.JRadioButton;

$/**$

$*$

$*$ @author Mohammed.Talaat $($mtala$3$t$)$

$*$ @version $1\mathrm{.}0$

$*/$

public class MainScreen extends JFrame implements ActionListener $\{$

private static final long serialVersionUID $=-1299314404835604855$L;

JRadioButton levels$[]=$ new JRadioButton$[3]$;

String levelStrings$[]=\{$ "Easy", "Normal", "Hard" $\}$;

MainScreenPanel buttonPanel $=$ null;

public MainScreen$()\{$

buttonPanel $=$ new MainScreenPanel$()$;

setDefaultCloseOperation$($JFrame$.$EXIT$\_$ON$\_$CLOSE$)$;

setBounds$(320,127,600,400)$;

setResizable$($false$)$;

buttonPanel.setBackground$($Color$.$BLACK$)$;

for $($int i $=0$; i $<$ levels.length; i$++)\{$

levels$[$i$]=$ new JRadioButton$($levelStrings$[$i$])$;

levels$[$i$].$addActionListener$($this$)$;

levels$[$i$].$setBackground$($Color$.$YELLOW$)$;

levels$[$i$].$setBounds$(260,200+$ i $*50,80,30)$;

buttonPanel.add$($levels$[$i$])$;

$\}$

buttonPanel.setLayout$($null$)$;

getContentPane$().$add$($buttonPanel$)$;

setVisible$($true$)$;

$\}$

public void actionPerformed$($ActionEvent e$)\{$

Object obj $=$ e$.$getSource$()$;

if $($obj $==$ levels$[0])\{$

new GameBoardWindow$(1)$;

setVisible$($false$)$;

dispose$()$;

$\}$

if $($obj $==$ levels$[1])\{$

new GameBoardWindow$(2)$;

setVisible$($false$)$;

dispose$()$;

$\}$

if $($obj $==$ levels$[2])\{$

new GameBoardWindow$(3)$;

setVisible$($false$)$;

dispose$()$;

$\}$

$\}$

@SuppressWarnings$("$serial$")$

class MainScreenPanel extends JPanel $\{$

MainScreenPanel$()\{$

$\}$

public void paintComponent$($Graphics g$)\{$

super.paintComponent$($g$)$;

Graphics$2$D g$2=($Graphics$2$D$)$ g;

g$2.$setColor$($Color$.$RED$)$;

g$2.$setFont$($new Font$("$Comic Sans MS$",$ Font.BOLD, $45))$;

g$2.$drawString$("$Snake$2$D Game", $135,85)$;

g$2.$setColor$($Color$.$ORANGE$)$;

g$2.$drawString$("$mtala$3$t$",210,150)$;

$\}$

$\}$

$\}$