Update a variable once a day?

Question

Java

How to update a variable once a day, when the program enters?

Answer 1

1. Check the last update date of a variable
   
2. If more than a day has passed between the current date and the update date, update the variable and update the update date.
   

Answer 2

now it is necessary that the change itself is updated once a day, for example at 2 am

for android you can use https://developer.android.com/training/scheduling/...