Mapping of Apache POI HSSF/XSSF to XLS/XLSX

Question

Apache POI 4.x here. I see there are two types of Workbook implementations:

• HSSF Workbook
• XSSF Workbook

I need to write a Java 8 app that reads Excel sheets with either " .xls " (XLS) or " .xlsx " (XLSX) extensions. Meaning, Excel files that were saved in the "old" (pre 2003) format, or the newer one.

Is it safe to assume I use HSSF for XLS files, and XSSF for XLSX files? Or is the mapping logic a little bit more complicated there? This answer seems to indicate I'm correct, but that doesn't leave me feeling totally sure that I understand the mapping and "when to use" logic of HSSF vs XSSF.

I've scoured the POI documentation but can't find a clear answer for the life of me.

Answer 1

HSSF ( org.apache.poi.hssf.usermodel package) is for XLS files format

XSSF ( org.apache.poi.xssf.usermodel package) is for XLSX files format (newer one)

Model classes from both packages (xssf and hssf) implements common interfaces from org.apache.poi.ss.usermodel package. So, you potentially can write a code using ss package and it will work with abstractions over xssf or hssf.