java - Creating a unique date each time between calls -

i writing java program using selenium. need function returns unique date (mm/dd/yyyy) each time called. conditions though that

1. it can never return date returned before
2. is must return date between 01/01/2071 , 12/31/9999
3. the program run many times program memory lost upon termination. must remember dates has returned before. see next item
4. the easiest way keep incrementing date 1 day each time, needs remember 1 date.
5. unfortunately cannot write last date returned file in system read next time program runs because not have ability.
6. the program reading data excel spreadsheet theoretically store latest date in cell, spreadsheet open , not seem have ability write open file.

any thoughts? 1 thing thought doing using base date 1/1/2014 @ 00:00:00 , taking current date, calculating number of minutes between two, , adding number of days 11/31/2070. unfortunately work couple of years because there more minutes between 2 dates there days 1/1/2017 12/31/9999

any appreciated.

thanks