The difference between 2 Instants in Calendar Days

Question

So I'm trying to get a specific number with my code. Right now I have:

Instant Today = 2018-07-17T13:45:00Z
Instant Expiration1 = 2018-07-18T11:00:00Z
long daysTilExp = Today.until(Expiration, Chronounit.DAYS)

The problem is that because this isn't exactly 24 hours apart it ends up returning daysTilExp = 0 but I want daysTilExp = 1 I'm trying to get that actual days apart the two Instants are so then even If I change the value of Expiration like so:

Instant Expiration1 = 2018-07-18T06:00:00Z

and now daysTilExp = 2. I looked at some other answers on StackOverflow but it doesn't look like people are using Instant and they aren't wanting the difference the same way

Answer 1

LocalDate will remove the time part and LocalDate objects comparison will yield the expected result:

LocalDateTime  today = LocalDateTime.parse("2018-07-17T13:45:00");
LocalDateTime  expiration = LocalDateTime.parse("2018-07-18T11:00:00");
LocalDate todayDate = today.toLocalDate();
LocalDate expirationDate = expiration.toLocalDate();
long days = todayDate.until(expirationDate, ChronoUnit.DAYS);
System.out.println(days);

Answer 2

The best way is using DAYS.between() method from java.time.temporal.ChronoUnit. But this way works only for Java 8+ versions. Example:

Date start = new Date();
Date end = new Date(start.getTime() + 10_000);
long daysCount = DAYS.between(start.toInstant(), end.toInstant());