The autoSizeColumn method deals only with the last rows flushed. I would like do an autosize when all rows are flushed. It's not possible with POI-3.8 beta 4 and an SXSSFWorkbook.
This is as expected. SXSSF only has the un-flushed data around to decide based on. If it kept more, then you'd loose all the memory benefits! You should either use regular XSSF (and ensure you have enough memory), or adjust the flush size
FYI: This has been solved in 3.14beta1, see #57450 .
*** This bug has been marked as a duplicate of bug 57450 ***