Formatting a Duration in Java 8 / jsr310
I am transitioning a project from Joda-Time to java8's native time libraries, and I have run into a snag.
I have been unable to find a formatter for Duration. I would like to have a custom String format of, for instance, HHH+MM, where a Duration of 75 hours and 15 minutes would format as "75+15".
This was easy to do with Joda-Time by converting to period, and using a PeriodFormatter, but I have been unable to find this type of class in Java8. Am I missing something?
Java 9 and later: Duration::to…Part methods
In Java 9 the Duration class gained new to…Part methods for returning the various parts of days, hours, minutes, seconds, milliseconds/nanoseconds. See this pre-release OpenJDK source code.
Given a duration of 49H30M20.123S…
-
toNanosPart()= 123000000 -
toMillisPart()= 123 -
toSecondsPart()= 20 -
toMinutesPart()= 30 -
toHoursPart()= 1 -
toDaysPart()= 2
Remember that “days” here means chunks of 24-hours, ignoring dates on a calendar. If you care about dates, use Period class instead.
I do not know if any additional formatter features are added. But at least you will be able to more conveniently generate your own strings from numbers obtained via these new getter methods.
Java 8
Oddly enough, no convenient getter methods for these values were included in the first edition release of java.time in Java 8. One of very few oversights in the otherwise excellent design of the java.time framework.
See the related Question: Why can't I get a duration in minutes or hours in java.time?.
There is no period/duration-formatter in jsr-310, different from JodaTime. Not every feature of JodaTime was ported to JSR-310 (for example also not PeriodType). And in reverse JSR-310 has some features which are not available in JodaTime (for example localized weekday numbers or the strategy pattern approach with adjusters).
It might happen that Java 9 will introduce some kind of built-in period formatting (read something about this from S. Colebourne).
Conclusion: JSR-310 and JodaTime are not fully compatible to each other, so a lot of work can be required. I would not be so keen on migration as soon as possible. Do you need special features of JSR-310 which are not offered by JodaTime?
Additional note: You should also be aware of the fact that joda period (which includes all units from years to seconds) is not fully compatible with jsr310-period (only years, months, days) or jsr310-duration (only hours, minutes, seconds and fraction seconds).