Groovy TimeCategory with LocalDate and LocalDateTime

Question

Are there any examples or links to using TimeCategory (or equivalent) with java8 LocalDate and LocalDateTime? All found code fragments belong to java.util.Date which I try to avoid.

Answer 1

With Java 8 manipulation, LocalDate is just as simple:

LocalDate.now().plusDays(2) 

I'm not sure if TimeCategory will win you?

---

You can just hack it into metaClass LocalDate and LocalDatTime:

 import groovy.time.* import java.time.* LocalDate.metaClass { plus { Duration d -> delegate.plusYears(d.years) .plusMonths(d.months) .plusDays(d.days) } } LocalDateTime.metaClass { plus { Duration d -> delegate.plusYears(d.years) .plusMonths(d.months) .plusDays(d.days) .plusHours(d.hours) .plusMinutes(d.minutes) .plusSeconds(d.seconds) } } use(TimeCategory) { LocalDateTime.now() + 4.days } 

Answer 2

Trivial example:

 import groovy.time.TimeCategory import java.time.LocalDate import java.time.LocalDateTime use( TimeCategory ) { println Date.parse('yyyy-MM-dd', LocalDate.now().toString()) + 4.hours println Date.parse("yyyy-MM-dd'T'hh:mm:ss", LocalDateTime.now().toString()) - 4.hours } 

Answer 3

I, too, was disappointed that TimeCategory declares it to be its own duration and does not support Java 8. This prompted me to write some of my own code, which I thought would be relevant to this issue. He focused on ZonedDateTime , not LocalDateTime because I was interested in the TimeZone logic, where I use it. This is not as complete as the groovy.time.TimeCategory class, and I only have a few operations that interest me, so feel free to add to them.

Without further ado:

 import java.time.Duration import java.time.ZoneOffset import java.time.ZonedDateTime import java.time.format.DateTimeFormatter import java.time.temporal.ChronoUnit class TimeCategory { static getDays(Integer self) { Duration.ofDays self } static getHours(Integer self) { Duration.ofHours self } static getMillis(Integer self) { Duration.ofMillis self } static getMinutes(Integer self) { Duration.ofMinutes self } static getNanos(Integer self) { Duration.ofNanos self } static getSeconds(Integer self) { Duration.ofSeconds self } static getWeeks(Integer self) { Duration.ofDays self * 7 } static getDay(Integer self) { Duration.ofDays self } static getHour(Integer self) { Duration.ofHours self } static getMilli(Integer self) { Duration.ofMillis self } static getMinute(Integer self) { Duration.ofMinutes self } static getNano(Integer self) { Duration.ofNanos self } static getSecond(Integer self) { Duration.ofSeconds self } static getWeek(Integer self) { Duration.ofDays self * 7 } static ZonedDateTime getAgo(Duration self) { ZonedDateTime.now() - self } static ZonedDateTime getUtc(ZonedDateTime self) { self.withZoneSameInstant(ZoneOffset.UTC) } static ZonedDateTime getLocal(ZonedDateTime self) { self.withZoneSameInstant(ZoneOffset.systemDefault()) } static ZonedDateTime getNow() { ZonedDateTime.now() } static Duration minus(ZonedDateTime self, ZonedDateTime other) { Duration.between(self, other) } static BigInteger getTotalNanos(Duration self) { self.seconds.toBigInteger() * 10 ** 9 + self.nano } static String toString(ZonedDateTime self, String pattern) { self.format(DateTimeFormatter.ofPattern(pattern)) } static Duration mod(Duration self, Duration other) { def (long seconds, int nanos) = (self.totalNanos % other.totalNanos).divideAndRemainder(10g.pow(9)) Duration.ofSeconds(seconds) + nanos.nanos } static load() { Integer.mixin(TimeCategory) ZonedDateTime.mixin(TimeCategory) Duration.mixin(TimeCategory) } } 

Usage example:

 // I prefer putting this in a start-up location and pollute the namespace rather than use // `use() {...}` TimeCategory.load() // Construct readable java 8 durations Duration d = 1.day + 2.hours + 3.minutes - 4.seconds // Easily construct dates relative to now ZonedDateTime yesterday = 1.day.ago // Of course, you can still call "unsugared" functions like truncatedTo for rounding down ZonedDateTime today = TimeCategory.now.truncatedTo(ChronoUnit.DAYS) // Converting between local and utc doesn't change the underlying instant assert 0.seconds == yesterday.utc - yesterday.local // Modulo arithmetic. Cool! assert 1.minute % 17.seconds == 9.seconds // Slightly cleaner date formatting println "Today in strange format ${today.toString('dd/yy/MM')}"