Hi, If you use HSSF to write to a file named ".xlsx" you likely actually write it in .xls binary format, but Excel automatically detects this and opens it anyway. Try unzipping the .xlsx to see if it is actually a zipped-xml-format.
You can use the base interfaces from the "org.apache.poi.ss.usermodel" package to do almost all things the same way for both formats, only the creation of new files needs to use HSSFWorkbook and XSSFWorkbook respectively, see e.g. the example at http://poi.apache.org/spreadsheet/converting.html#New%2C+generic+SS+Usermodel+Code And please use the poi-user-mailing-list instead of contacting people directly. Dominik. On Sun, Nov 13, 2016 at 5:52 PM, Markus Maria Michaels <[email protected]> wrote: > Hey, > > sorry bothering you. > > Can i use XSSF to export both, XLS and XLSX files without any problems ? > > (I had no problem to export a XLSX - file with HSSF so far.) > > Thanks a lot. >
