问题
All written DatePickerDialog report an error (cannot resolve symbol), but the program is compiled correctly, no error in the LogCat. Who can explain why?
回答1:
You should try the Invalidate Caches / Restart option on the File menu. A stale cache is the cause of many unresolved reference problems that are actually there.
来源：https://stackoverflow.com/questions/61661162/datepickerdialog-cannote-resolve-symbol