java - 关于Poi，Sheet的问题

Answer 1

If the three programs are executed in parallel, then each program will save the Excel after modifying it, so only the last saved Excel will be retained.
If the three programs are executed in series, then each program opens Excel first, then selects the sheet, then makes modifications, saves Excel after modification, and the next program is executed in this way again, how can overwriting occur?

Answer 2

If it is a multi-threaded file operation, lock the code that operates excel, read excel first, and then write.