Реализовать ничью в игре Крестики-Нолики - Java

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.Cursor;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
 
public class KrestikiNoliki {
    public static void main(String[] args) {
        KOFrame frame = new KOFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.show();               
    }
}
 
class KOFrame extends JFrame {
 
    JLabel score;
 
    public KOFrame() {
        Toolkit kit = Toolkit.getDefaultToolkit();
        Dimension ss = kit.getScreenSize();
        int scrW = ss.width;
        int scrH = ss.height;
 
        int fW = 300;
        int fH = 350;
    //  System.out.println((scrW - fW) / 2 +"    " + (scrH - fH) / 2);
 
        JFrame frame = new JFrame();
 
        score = new JLabel();
 
        setSize(fW, fH);
        setLocation((scrW - fW) / 2, (scrH - fH) / 2);
        setTitle("Крестики-нолики Баранова Е.");
        setCursor(Cursor.HAND_CURSOR);
 
        KOPanel panel = new KOPanel(this);
        Container contain = getContentPane();
        contain.add(panel);
        ExitPanel exit_panel = new ExitPanel(panel);
        contain.add(exit_panel, "South");
        add(score, BorderLayout.NORTH);
        refreshScore(0, 0);
    }
 
    public void refreshScore(int x, int o) {
        score.setText("     Крестики: " + x
                + "                                         Нолики: " + o);
    }
 
}
 
class ExitPanel extends JPanel {
    KOPanel koPanel;
 
    public ExitPanel(final KOPanel koPanel) {
        setLayout(new GridLayout(1, 2));
        KOButton exit = new KOButton(4, 4);
        KOButton restart = new KOButton(5, 5);
        this.koPanel = koPanel;
        add(restart);
        add(exit);
        exit.setText("Выход");
        restart.setText("Рестарт");
 
        exit.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
 
                System.exit(0);
            }
        });
 
        restart.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
 
                koPanel.clear();
                koPanel.clearGameScreen();
            }
        });
 
    }
}
 
class KOPanel extends JPanel {
    char[][] game_arr = new char[3][3];
    {
        for (int i = 0; i < 3; ++i) {
            for (int j = 0; j < 3; ++j) {
                game_arr[i][j] = ' ';
            }
        }
    }
 
    KOButton[][] buttons = new KOButton[3][3];
    public int cout = 0;
 
    ImageIcon krest = new ImageIcon("krestik i nolik/x.jpg");
    ImageIcon nol = new ImageIcon("krestik i nolik/o.jpg");
    ImageIcon start = new ImageIcon("/start_image.jpg");
 
    KOFrame koFrame; // ссылка на главный фрейм
    int xCount = 0; // победы Х
    int oCount = 0; // победы О
 
    public KOPanel(KOFrame koFrame) {
        this.koFrame = koFrame;
        setLayout(new GridLayout(3, 3));
 
        {
    for (int i = 0; i < 3; ++i) {
        for (int j = 0; j < 3; ++j) {
        buttons[i][j] = new KOButton(i, j);
        buttons[i][j].addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent event) {
                KOButton sourceOfAction = (KOButton) event
                    .getSource();
            if (cout % 2 == 0
                && game_arr[sourceOfAction.getRow()][sourceOfAction
                    .getColumn()] == ' ') {
                game_arr[sourceOfAction.getRow()][sourceOfAction
                    .getColumn()] = 'x';
                sourceOfAction.setIcon(krest);
                chek();
                cout++;
 
                    } else if (cout % 2 == 1
                    && game_arr[sourceOfAction.getRow()][sourceOfAction
                        .getColumn()] == ' ') {
                game_arr[sourceOfAction.getRow()][sourceOfAction
                        .getColumn()] = 'o';
                    sourceOfAction.setIcon(nol);
                    chek();
                    cout++;
                            }
                        }
                    });
            add(buttons[i][j]);
                }
            }
        }
    }
 
    public void chek() {
        String exit_option_string;
        int exit_option = 0;
 
        if ((game_arr[0][0] == 'x' && game_arr[0][1] == 'x' && game_arr[0][2] == 'x')
                || (game_arr[1][0] == 'x' && game_arr[1][1] == 'x' && game_arr[1][2] == 'x')
                || (game_arr[2][0] == 'x' && game_arr[2][1] == 'x' && game_arr[2][2] == 'x')
                || (game_arr[0][0] == 'x' && game_arr[1][0] == 'x' && game_arr[2][0] == 'x')
                || (game_arr[0][1] == 'x' && game_arr[1][1] == 'x' && game_arr[2][1] == 'x')
                || (game_arr[0][2] == 'x' && game_arr[1][2] == 'x' && game_arr[2][2] == 'x')
                || (game_arr[0][0] == 'x' && game_arr[1][1] == 'x' && game_arr[2][2] == 'x')
                || (game_arr[2][0] == 'x' && game_arr[1][1] == 'x' && game_arr[0][2] == 'x')) {
            JOptionPane.showMessageDialog(null, "Выиграли крестики!");
            clear();
            clearGameScreen();
            xCount++;
            koFrame.refreshScore(xCount, oCount);
        }
 
        if ((game_arr[0][0] == 'o' && game_arr[0][1] == 'o' && game_arr[0][2] == 'o')
                || (game_arr[1][0] == 'o' && game_arr[1][1] == 'o' && game_arr[1][2] == 'o')
                || (game_arr[2][0] == 'o' && game_arr[2][1] == 'o' && game_arr[2][2] == 'o')
                || (game_arr[0][0] == 'o' && game_arr[1][0] == 'o' && game_arr[2][0] == 'o')
                || (game_arr[0][1] == 'o' && game_arr[1][1] == 'o' && game_arr[2][1] == 'o')
                || (game_arr[0][2] == 'o' && game_arr[1][2] == 'o' && game_arr[2][2] == 'o')
                || (game_arr[0][0] == 'o' && game_arr[1][1] == 'o' && game_arr[2][2] == 'o')
                || (game_arr[2][0] == 'o' && game_arr[1][1] == 'o' && game_arr[0][2] == 'o')) {
            JOptionPane.showMessageDialog(null, "Выиграли нолики!");
            clear();
            clearGameScreen();
            oCount++;
            koFrame.refreshScore(xCount, oCount);
        }
 
    }
 
    public void clear() {
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                game_arr[i][j] = ' ';
            }
        }
    }
 
    public void clearGameScreen() {
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                buttons[i][j].setIcon(start);
            }
        }
    }
 
}
 
class KOButton extends JButton {
    public KOButton(int r, int c) {
        super();
        row = r;
        column = c;
    }
 
    public int getRow() {
        return row;
    }
 
    public int getColumn() {
        return column;
    }
 
    private int row, column;
}