I'm trying to save and reload the state of my Swing program, which in this case is a Minesweeper game. My code for the board is below.

package mines;

import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import java.util.Random;

import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class Board extends JPanel {

    public static void main (String[] args)  {}
    private final int NUM_IMAGES = 13;
    private final int CELL_SIZE = 15;

    private final int COVER_FOR_CELL = 10;
    private final int MARK_FOR_CELL = 10;
    private final int EMPTY_CELL = 0;
    private final int MINE_CELL = 9;
    private final int COVERED_MINE_CELL = MINE_CELL + COVER_FOR_CELL;
    private final int MARKED_MINE_CELL = COVERED_MINE_CELL + MARK_FOR_CELL;

    private final int DRAW_MINE = 9;
    private final int DRAW_COVER = 10;
    private final int DRAW_MARK = 11;
    private final int DRAW_WRONG_MARK = 12;

    private int[] field;
    private boolean inGame;
    private int mines_left;
    private Image[] img;
    private int mines = 40;
    private int rows = 16;
    private int cols = 16;
    private int all_cells;
    private JLabel statusbar;

    public Board(JLabel statusbar) {

        this.statusbar = statusbar;

        img = new Image[NUM_IMAGES];

        for (int i = 0; i  0) { 
                cell = position - 1 - cols;
                if (cell >= 0)
                    if (field[cell] != COVERED_MINE_CELL)
                        field[cell] += 1;
                cell = position - 1;
                if (cell >= 0)
                    if (field[cell] != COVERED_MINE_CELL)
                        field[cell] += 1;

                cell = position + cols - 1;
                if (cell = 0)
                if (field[cell] != COVERED_MINE_CELL)
                    field[cell] += 1;
            cell = position + cols;
            if (cell = 0)
                    if (field[cell] != COVERED_MINE_CELL)
                        field[cell] += 1;
                cell = position + cols + 1;
                if (cell  0) { 
        cell = j - cols - 1;
        if (cell >= 0)
            if (field[cell] > MINE_CELL) {
                field[cell] -= COVER_FOR_CELL;
                if (field[cell] == EMPTY_CELL)
                    find_empty_cells(cell);
            }

        cell = j - 1;
        if (cell >= 0)
            if (field[cell] > MINE_CELL) {
                field[cell] -= COVER_FOR_CELL;
                if (field[cell] == EMPTY_CELL)
                    find_empty_cells(cell);
            }

        cell = j + cols - 1;
        if (cell  MINE_CELL) {
                field[cell] -= COVER_FOR_CELL;
                if (field[cell] == EMPTY_CELL)
                    find_empty_cells(cell);
            }
    }

      cell = j - cols;
    if (cell >= 0)
        if (field[cell] > MINE_CELL) {
            field[cell] -= COVER_FOR_CELL;
            if (field[cell] == EMPTY_CELL)
                find_empty_cells(cell);
        }

       cell = j + cols;
       if (cell  MINE_CELL) {
            field[cell] -= COVER_FOR_CELL;
            if (field[cell] == EMPTY_CELL)
                find_empty_cells(cell);
           }

          if (current_col = 0)
               if (field[cell] > MINE_CELL) {
                field[cell] -= COVER_FOR_CELL;
                if (field[cell] == EMPTY_CELL)
                    find_empty_cells(cell);
            }

           cell = j + cols + 1;
            if (cell  MINE_CELL) {
                field[cell] -= COVER_FOR_CELL;
                if (field[cell] == EMPTY_CELL)
                    find_empty_cells(cell);
            }

          cell = j + 1;
           if (cell  MINE_CELL) {
                field[cell] -= COVER_FOR_CELL;
                if (field[cell] == EMPTY_CELL)
                    find_empty_cells(cell);
               }
        }

       }

      public void paint(Graphics g) {

       int cell = 0;
        int uncover = 0;


        for (int i = 0; i  COVERED_MINE_CELL) {
                    cell = DRAW_WRONG_MARK;
                } else if (cell > MINE_CELL) {
                    cell = DRAW_COVER;
                }


            } else {
                if (cell > COVERED_MINE_CELL)
                    cell = DRAW_MARK;
                else if (cell > MINE_CELL) {
                    cell = DRAW_COVER;
                    uncover++;
                }
            }

            g.drawImage(img[cell], (j * CELL_SIZE),
                (i * CELL_SIZE), this);
        }
       }


      if (uncover == 0 && inGame) {
        inGame = false;
        statusbar.setText("Game won");
      } else if (!inGame)
        statusbar.setText("Game lost");
       }




     class MinesAdapter extends MouseAdapter {
       public void mousePressed(MouseEvent e) {

        int x = e.getX();
        int y = e.getY();

        int cCol = x / CELL_SIZE;
        int cRow = y / CELL_SIZE;

        boolean rep = false;


          if (!inGame) {
            newGame();
            repaint();
          }


         if ((x  MINE_CELL) {
                    rep = true;

                    if (field[(cRow * cols) + cCol]  0) {
                            field[(cRow * cols) + cCol] += MARK_FOR_CELL;
                            mines_left--;
                            statusbar.setText(Integer.toString(mines_left));
                        } else
                            statusbar.setText("No marks left");
                    } else {

                        field[(cRow * cols) + cCol] -= MARK_FOR_CELL;
                        mines_left++;
                        statusbar.setText(Integer.toString(mines_left));
                    }
                }

            } else {

                if (field[(cRow * cols) + cCol] > COVERED_MINE_CELL) {
                    return;
                }

                if ((field[(cRow * cols) + cCol] > MINE_CELL) &&
                    (field[(cRow * cols) + cCol]