If you add days to a LocalDate, the month and year fields are adjusted to keep the result a valid date.
import java.time.LocalDate; import java.time.Month; public class Main { public static void main(String[] args) { LocalDate ld1 = LocalDate.of(2014, Month.JANUARY, 31); LocalDate ld2 = ld1.plusDays(30); LocalDate ld3 = ld1.plusDays(555); System.out.println(ld1);//from w ww. ja v a 2 s.c om System.out.println(ld2); System.out.println(ld3); } }