Use LocalDate and ChronoUnit:
LocalDate date1 = LocalDate.of(2018, 8, 10); LocalDate date2 = LocalDate.of(2018, 8, 30);
As long as the method between of the ChronoUnit enumerator takes 2 Temporals as parameters so you can pass the LocalDate instances without a problem.
long days = ChronoUnit.DAYS.between(date1, date2); System.out.println(days);