NoughtsCrosses Compilation Errors

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

import javax.swing.*;


public class NoughtsCrosses implements ActionListener {

    //variable setup for GUI + game
    JFrame frame = new JFrame("Noughts and Crosses");
    JButton square[] = new JButton[9];
    JPanel panel = new JPanel();
    JPanel grid = new JPanel(new GridBagLayout());
    JLabel playergo = new JLabel("It is player 1's go!");
    String letter = ("");;

    private boolean win = false;
    int move = 0;
    int player;

    public NoughtsCrosses() {
        //GUI setup
        frame.setSize(300,300);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(false);
        frame.setLocationRelativeTo(null);
        frame.add(grid);

        //set up panel grid w/ gridbagconstraints, c
        panel = new JPanel();
        panel.setBackground(Color.WHITE);
        GridBagConstraints c = new GridBagConstraints();
        grid.setPreferredSize(new Dimension(270, 180));

        //put the squares into the grid, labelled 0-1-2 | 3-4-5 | 6-7-8
        for(int n = 0; n < 3; n++) {
            square[n] = new JButton();
            square[n].setText("");
            c.gridx=n; c.gridy=0;
            square[n].setPreferredSize(new Dimension (90, 60));
            grid.add(square[n], c);
            square[n].addActionListener(this);
            }

            for(int n = 3 ;n < 6; n++) {
            square[n] = new JButton();
            square[n].setText("");
            c.gridx=(n-3); c.gridy=1;
            square[n].setPreferredSize(new Dimension (90, 60));
            grid.add(square[n], c);
            square[n].addActionListener(this);
            }

            for(int n =6 ; n < 9; n++) {
            square[n] = new JButton();
            square[n].setText("");
            c.gridx=(n-6); c.gridy=2;
            square[n].setPreferredSize(new Dimension (90, 60));
            grid.add(square[n], c);
            square[n].addActionListener(this);
            }

            //bar at top to show who's go it is

        playergo.setFont(new Font("Arial", Font.PLAIN, 16));
        playergo.setBackground(Color.WHITE);
        playergo.setForeground(Color.BLACK);
        frame.getContentPane().add(playergo, BorderLayout.NORTH);
        playergo.setHorizontalAlignment(JTextField.CENTER);
        }


    public void actionPerformed (ActionEvent e) {
        //one more move has gone by, calculate player turn + player letter
        move++;

        if (move % 2 == 0 || move == 0) {
            player = 1; letter = "X";
        }else{
            player = 2; letter = "O";
        }

        playergo.setText("It is player " + player + "'s go!");

        //set square letter to player's letter, disable square so no further moves can be made there
        for (int n=0; n<=8; n++){
            if (e.getSource() == square[n]){
                square[n].setText(letter);
                square[n].setEnabled(false);
            }
        }

        for(int n=0; n<=7; n++){
            if( square[winningLines[n][0]].getText().equals(square[winningLines[n][1]].getText()) &&
                square[winningLines[n][1]].getText().equals(square[winningLines[n][2]].getText()) &&
                square[winningLines[n][0]].getText() != ""){
                win = true;
            }
        }


        //set end game conditions, and disable all squares in the event of a win
    if (win == true) {
        playergo.setText("Player " + player + " has won!");
        for (int n = 0; n < 9; n++) {
            square[n].setEnabled(false);
        }
    }else if (win == false && move == 9) {
        playergo.setText("Draw game. Play again?");
        }

    }//ActionPerformed method body

    int winningLines[][] = {{0,1,2}, {3,4,5}, {6,7,8}, {0,3,6}, {1,4,7}, {2,5,8}, {0,4,8}, {2,4,6}};

    public static void main(String[] args){
        new NoughtsCrosses();
    }//main body

}//NoughtsCrosses class body