Android app for college assignments first

-There is an error when the application button is clicked without inputting any number.
-÷ symbol does not output the calculated value in [Full + Formula = Fullmula]
-If the log record is emptied individually, there is an error in overwriting the record in the next log record during the next save.
-Screen slides up when taking input device out of some devices
-There is an error that is not saved in the log record if the switch is not operated once after running the app.
-Switch not changed to 1 when AC button is pressed
-There may be various errors that the developer does not know about
-I don't know why it violates operating policy