Convert the date to epoch days.
The epoch days is the number of days from 1970-01-01 to a date.
A date before 1970-01-01 returns a negative integer.
import java.time.LocalDate; public class Main { public static void main(String[] args) { LocalDate ld = LocalDate.of(2020, 5, 2); // 2020-05-02 long epochDays = ld.toEpochDay(); System.out.println(epochDays); }/*from www . j a v a2 s . c o m*/ }