Java 8: Difference Between Two Localdatetime in Multiple Units

Java 8: Difference between two LocalDateTime in multiple units

Unfortunately, there doesn't seem to be a period class that spans time as well, so you might have to do the calculations on your own.

Fortunately, the date and time classes have a lot of utility methods that simplify that to some degree. Here's a way to calculate the difference although not necessarily the fastest:

LocalDateTime fromDateTime = LocalDateTime.of(1984, 12, 16, 7, 45, 55);
LocalDateTime toDateTime = LocalDateTime.of(2014, 9, 10, 6, 40, 45);

LocalDateTime tempDateTime = LocalDateTime.from( fromDateTime );

long years = tempDateTime.until( toDateTime, ChronoUnit.YEARS );
tempDateTime = tempDateTime.plusYears( years );

long months = tempDateTime.until( toDateTime, ChronoUnit.MONTHS );
tempDateTime = tempDateTime.plusMonths( months );

long days = tempDateTime.until( toDateTime, ChronoUnit.DAYS );
tempDateTime = tempDateTime.plusDays( days );

long hours = tempDateTime.until( toDateTime, ChronoUnit.HOURS );
tempDateTime = tempDateTime.plusHours( hours );

long minutes = tempDateTime.until( toDateTime, ChronoUnit.MINUTES );
tempDateTime = tempDateTime.plusMinutes( minutes );

long seconds = tempDateTime.until( toDateTime, ChronoUnit.SECONDS );

System.out.println( years + " years " + 
        months + " months " + 
        days + " days " +
        hours + " hours " +
        minutes + " minutes " +
        seconds + " seconds.");

//prints: 29 years 8 months 24 days 22 hours 54 minutes 50 seconds.

The basic idea is this: create a temporary start date and get the full years to the end. Then adjust that date by the number of years so that the start date is less then a year from the end. Repeat that for each time unit in descending order.

Finally a disclaimer: I didn't take different timezones into account (both dates should be in the same timezone) and I also didn't test/check how daylight saving time or other changes in a calendar (like the timezone changes in Samoa) affect this calculation. So use with care.

Get difference of seconds beetween two dateTime

int seconds = (int) ChronoUnit.SECONDS.between(now, midnight); 

Storing difference between two LocalDateTime values

The correct way is to decompose the difference by time unit such as in this answer.

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Another option would be to save the date difference in a period and the time difference in a duration but this may lead to negative units in some cases:

LocalDateTime now = LocalDateTime.now();
LocalDateTime before = now.minusMonths(1).minusDays(5).minusHours(2).minusMinutes(30);
Period p = Period.between(before.toLocalDate(), now.toLocalDate());
Duration d = Duration.between(before.toLocalTime(), now.toLocalTime());

System.out.println(p + " + " + d);

which outputs: P1M5D + PT2H30M

Corner cases: if before = now.minusMonths(1).plusDays(1).plusMinutes(30);, the duration is minus 30 minutes. This can't easily be fixed because doing an intuitive:

if (d.isNegative()) {
  p = p.minusDays(1);
  d = d.plusDays(1);
}

Can return negative days in other cases.

Java: time difference in milliseconds using LocalDateTime and ChronoUnit

I think the last param there is actually nano seconds:
https://docs.oracle.com/javase/8/docs/api/java/time/LocalDateTime.html#of-int-java.time.Month-int-int-int-int-int-

Switching to a diff of nanos output 2 in my case:

LocalDateTime startDate = LocalDateTime.of(2017, 11, 22, 21, 30, 30, 250);
LocalDateTime endDate = LocalDateTime.of(2017, 11, 22, 21, 30, 30, 252);
long diff = ChronoUnit.NANOS.between(startDate, endDate);

System.out.println(diff);

Yields:

2

I think that since you are comparing millis, the diff is being rounded down.

Java Subtracting LocalDateTime foo from LocalDateTime Bar

Why do you not simply use directly LocalDateTime as parameter type this way:

LocalDateTime start = new LocalDateTime(2016, 10, 4, 17, 45);
LocalDateTime end = LocalDateTime.now();
PeriodType ptype = PeriodType.yearMonthDayTime();
Period diff = new Period(start, end, ptype);

See also the API of Joda-Time. You don't need to cast to DateTime.

Calculating the difference between two Java date instances

The JDK Date API is horribly broken unfortunately. I recommend using Joda Time library.

Joda Time has a concept of time Interval:

Interval interval = new Interval(oldTime, new Instant());

EDIT: By the way, Joda has two concepts: Interval for representing an interval of time between two time instants (represent time between 8am and 10am), and a Duration that represents a length of time without the actual time boundaries (e.g. represent two hours!)

If you only care about time comparisions, most Date implementations (including the JDK one) implements Comparable interface which allows you to use the Comparable.compareTo()

Calculate days between two Dates in Java 8

If you want logical calendar days, use DAYS.between() method from java.time.temporal.ChronoUnit:

LocalDate dateBefore;
LocalDate dateAfter;
long daysBetween = DAYS.between(dateBefore, dateAfter);

If you want literal 24 hour days, (a duration), you can use the Duration class instead:

LocalDate today = LocalDate.now()
LocalDate yesterday = today.minusDays(1);
// Duration oneDay = Duration.between(today, yesterday); // throws an exception
Duration.between(today.atStartOfDay(), yesterday.atStartOfDay()).toDays() // another option

For more information, refer to this document.

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