Please fill out the code in java $($TicTacToeGUI$.$java$).$ Thank you!

TicTacToeGUI.java $($private class State should not be altered!$)$:

import javax.swing.JFrame;

import javax.swing.JButton;

import javax.swing.JOptionPane;

import java.awt.GridLayout;

import java.awt.event.ActionListener;

import java.awt.event.ActionEvent;

public final class TicTacToeGUI $\{$

public static void main$($String$[]$ args$)\{$

TicTacToeGUI t $=$ new TicTacToeGUI$()$;

$\}$

private State state;

private GUI gui;

private void startNewGame$()\{$

if $($gui $!=$ null$)\{$

gui.dispose$()$;

$\}$

state $=$ new State$()$;

gui $=$ new GUI$()$;

$\}$

$//$ step $1.$ define our custom default constructor for TicTacToeGUI

$//$ we can simply call the startNewGame in this default constructor

$//$ so that data members will be initialzed

$//$ the state class manages the logic part of this game $($do not alter the code within this class$)$

private class State $\{$

private char XO $=\text{'}$X$\text{'}$;

private void prepareForNextMove$()\{$

XO $=($XO $==\text{'}$X$\text{'})?\text{'}$O$\text{'}$ : $\text{'}$X$\text{'}$;

$\}$

private final char$[][]$ board $=$ new char$[][]\{\{\text{'}\text{'},\text{'}\text{'},\text{'}\text{'}\},$

$\{\text{'}\text{'},\text{'}\text{'},\text{'}\text{'}\},$

$\{\text{'}\text{'},\text{'}\text{'},\text{'}\text{'}\}\}$;

private void applyMove$($int row, int col$)\{$

board$[$row$][$col$]=$ XO;

$\}$

private boolean someoneWon$()\{$

if $(\text{'}\text{'}!=$ board$[0][0]$ && board$[0][0]==$ board$[0][1]$ && board$[0][1]==$ board$[0][2])\{$

return true;

$\}$

if $(\text{'}\text{'}!=$ board$[1][0]$ && board$[1][0]==$ board$[1][1]$ && board$[1][1]==$ board$[1][2])\{$

return true;

$\}$

if $(\text{'}\text{'}!=$ board$[2][0]$ && board$[2][0]==$ board$[2][1]$ && board$[2][1]==$ board$[2][2])\{$

return true;

$\}$

if $(\text{'}\text{'}!=$ board$[0][0]$ && board$[0][0]==$ board$[1][0]$ && board$[1][0]==$ board$[2][0])\{$

return true;

$\}$

if $(\text{'}\text{'}!=$ board$[0][1]$ && board$[0][1]==$ board$[1][1]$ && board$[1][1]==$ board$[2][1])\{$

return true;

$\}$

if $(\text{'}\text{'}!=$ board$[0][2]$ && board$[0][2]==$ board$[1][2]$ && board$[1][2]==$ board$[2][2])\{$

return true;

$\}$

if $(\text{'}\text{'}!=$ board$[0][0]$ && board$[0][0]==$ board$[1][1]$ && board$[1][1]==$ board$[2][2])\{$

return true;

$\}$

if $(\text{'}\text{'}!=$ board$[0][2]$ && board$[0][2]==$ board$[1][1]$ && board$[1][1]==$ board$[2][0])\{$

return true;

$\}$

return false;

$\}$

private boolean boardFull$()\{$

return board$[0][0]!=\text{'}\text{'}$ && board$[0][1]!=\text{'}\text{'}$ && board$[0][2]!=\text{'}\text{'}$ &&

board$[1][0]!=\text{'}\text{'}$ && board$[1][1]!=\text{'}\text{'}$ && board$[1][2]!=\text{'}\text{'}$ &&

board$[2][0]!=\text{'}\text{'}$ && board$[2][1]!=\text{'}\text{'}$ && board$[2][2]!=\text{'}\text{'}$;

$\}$

$\}$

$//$ GUI is reponsible for the user interaction

$//$ step $2.$ provide a default constructor for class GUI

$//$ important parts

$//$ a$.$ GUI is a subclass of JFrame, in the default contructor

$//$ set the basic setting for JFrame, e$.$g$.$ setSize, setTitle, setDefaultCloseOperation and so on

$//$ b$.$ make use to Grid layout for JFrame$/$JPanel$,3$x$3$ grid

$//$ c$.$ need to add $9$ custom buttons $($Tile$)$ in total for this grid, inital text part $""$

$//$ step $3.$ implement our custom button $($Tile$)$

$//$ a$.$ provide a row and col data member for Tile so that we can know which button we are clicking

$//$ b$.$ provide an action listener for it

$//$ b$1.$ implement our custom action listener, override the actionPerformed method

$//$ b$2.$ tell what is the source button of this event $($getSource$())$

$//$ b$3.$ check if this button has been occupied by a previous move

$//$ b$4.$ if occupied, show up a dialog telling user about this

$//$ b$5.$ if not occupied, change the text part to be $\text{'}$X$\text{'}$ or $\text{'}$O$\text{'}$ by using setText$()$ Method

$//$ b$6.$ call processValidMove method to hanld status

$//$ step $4.$ change the status as well, this part should be implemented in processValidMove

$//$ if it's a draw, show up a dialog, start a new game

$//$ if someone wins, also show up a dialog, start a new game

$//$ if the game is not finished, prepare for the next move

private class GUI extends JFrame $\{$

private class Tile extends JButton$\{$

$\}$

$\}$

private void processValidMove$($int row, int col$)\{$

$\}$

$\}$