private boolean checkDiagonal(int startIndex) {
        int countOfCross = 0;
        int countOfZero = 0;
        int j;
        for (int i = 0; i < board.length; i++) {
            if (startIndex == 0) {
                j = i;
            } else {
                j = 2 - i;
            }
            switch (board[i][j]) {
                case CROSS:
                    countOfCross++;
                    break;
                case ZERO:
                    countOfZero++;
                    break;
            }
        }
        if (countOfCross == 3 || countOfZero == 3)
            return true;
        return false;
    }