EastAsianCalendar cannot operate on time units smaller than a day.

[Charlweed]

I was trying to use the plus method on ChineseCalendar to add a number of seconds, and there does not seem to be any way. At least not in 4.99-beta. ChineseCalendar.Unit ChineseCalendar.Unit has no unit smaller than DAYS. None of the arithmetic methods will accept any argument types except ChineseCalendar.Unit, and there is no way to convert other units into ChineseCalendar.Unit. This effectually blocks any operations with ClockUnit on units of time smaller than an day. I'm hacking around on the source to see what happens when I insert hours-minutes-seconds into the ChineseCalendar.Unit enum, but it is unclear why there are different incompatible types for:

net.time4j.CalendarUnit net.time4j.ClockUnit net.time4j.calendar.ChineseCalendar.Unit

and no ChineseCalendar ClockUnit at all.

[MenoData]

In general, the units associated with calendars have no finer granularity than days because calendars itself don't bother about clock time. Calendars are not designed for this purpose.

But you can combine calendars with clock time to a general timestamp for example the following way:

GeneralTimestamp<ChineseCalendar> tsp = chineseCalendar.atTime(19, 45);

There is also a more general at(PlainTime)-method available. Once you have a general timestamp, you can either extract the calendar component or the (iso) clock time, or you can convert it to a Moment (with specifying the timezone and the start of day).

Two special calendars also have special time units via extension classes:

• EthiopianTime
• HebrewTime

Historically, Chinese people (and other East Asian peoples, too) had also used other time units which are not compatible with western clock units, but this has not (yet?) been implemented in Time4J.

[MenoData]

By the way, the type CalendarUnit only handles ISO-calendar units where the month-based units are totally different from the Chinese month units. We should not mix both units in order to guarantee minimum compile-time type safety.

[MenoData]

About time arithmetic with plus()- or minus()-methods, this has not (yet?) been implemented in the class GeneralTimestamp but you can of course convert your calendar to a Moment and then apply time arithmetic in the physical space. Example:

GeneralTimestamp<ChineseCalendar> tsp = chineseCalendar.atTime(19, 45);
Moment moment = tsp.in(Timezone.ofSystem(), StartOfDay.MIDNIGHT);
Moment twoHoursLater = moment.plus(2, TimeUnit.HOURS);

[Charlweed]

Thank you!

Perhaps I will try that approach.

Dev

From: Meno Hochschild [mailto:notifications@github.com] Sent: Tuesday, September 11, 2018 12:45 AM To: MenoData/Time4J Time4J@noreply.github.com Cc: Charlweed Hymerfan dev@hymes.name; Author author@noreply.github.com Subject: Re: [MenoData/Time4J] EastAsianCalendar cannot operate on time units smaller than a day. (#810)

About time arithmetic with plus()- or minus()-methods, this has not (yet?) been implemented in the class GeneralTimestamp but you can of course convert your calendar to a Moment and then apply time arithmetic in the physical space.

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[MenoData]

As you see, I have added another example above which demonstrates how to realize addition of time units on a Chinese calendar. I am not sure however, if an extra method in the class GeneralTimestamp is worth the effort because the signature of such a method has also to accept two extra parameters for the time zone and maybe even the start of day if deviating from the calendar standard. Feel free to make suggestions for either such a method or instead more documentation.

[MenoData]

Okay, I have now added some time arithmetic to the class GeneralTimestamp directly for convenience. But if you want clock units in physical space (taking time zones into account) then please follow my advise to first convert to Moment.