How to use text extraction strategy

Question

I am stuck in itext7 custom strategy. My goal is to extract data from a PDF to a text file without losing the table format. My PDF has a different table structure, some table columns are horizontal and some table structure is vertical. How can I control this? My requirement is to turn the PDF table into text format without losing any table format. I am successful in turning the PDF turn into text format, but the PDF table loses its table format. Also, if column value is empty, how can I handle this situation?