private boolean boardIsFull()
  {
    for (int x=0; x < boardWidth; x++)
    {
      for (int y=0; y < boardWidth; y++)
      {
        if (sudokuTextFields[y][x].getText() == null || sudokuTextFields[y][x].getText().isEmpty() || boardVals[y][x] == NULL_VAL)
          return false;
      }
    }
    return true;
  }