Java 8: Difference between two LocalDateTime in multiple units

I found the best way to do this is with ChronoUnit.

long minutes = ChronoUnit.MINUTES.between(fromDate, toDate);long hours = ChronoUnit.HOURS.between(fromDate, toDate);

Additional documentation is here: https://docs.oracle.com/javase/tutorial/datetime/iso/period.html

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.

It should be simpler!

Duration.between(startLocalDateTime, endLocalDateTime).toMillis();

You can convert millis to whatever unit you like:

String.format("%d minutes %d seconds",   TimeUnit.MILLISECONDS.toMinutes(millis),  TimeUnit.MILLISECONDS.toSeconds(millis) -   TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millis)));