Calculation problem

[lsgmkk]

I have a question, when using this library to calculate HijrahDate, sometimes it is a day late. E.g Convert today 2020-1-7 to HijrahDate: 1441-5-12 But the result calculated using this library is: 1441-5-11 What is the reason at this time?

[catull]

Can you show some code ?

Java 8+ bases the Hijrah calendar of the "Umm al-Qura". It is a calculation-based calendar.

It is therefore not based on the actual sighting of the lunar crescent (hilāl).

I see you already asked the question here: https://github.com/JakeWharton/ThreeTenABP/issues/118 There the platform is Android, which is based on Java 6.

I see you are not specifying any time zone, not sure if it changes anything. Also, Androids DateTimeFormatter may be based on UTC, and thus a day starts at midnight, whereas the Islamic calendar considers sunset to be cut-off.

Do you remember when exactly you tried your code ?

[catull]

This page https://www.al-habib.info/islamic-calendar/ummulqura/islamic-calendar-ummulqura-2020-ce.htm gives Jan 7th 2020 as 1441-05-12, as you expect it.

[lsgmkk]

I have a problem using JakeWharton / ThreeTenABP I configured the source code using java8 JakeWharton called me here to find the answer Any suggestions for Android?

[lsgmkk]

This is my code：

@RequiresApi(Build.VERSION_CODES.O)
fun test() {
    var hijrahDate = HijrahDate.now()
    var of1 = org.threeten.bp.LocalDate.of(2020, 2, 24)
    var date1 = HijrahDate.from(of1)
    var pattern = org.threeten.bp.format.DateTimeFormatter.ofPattern("MM/dd/yyyy")
    var s = pattern.format(date1)

    Log.e("TAG", "test 1-------->$s")

    var ofPattern = DateTimeFormatter.ofPattern("MM/dd/yyyy")
    var now = java.time.chrono.HijrahDate.now()
    var of = LocalDate.of(2020, 2, 24)
    var date = java.time.chrono.HijrahDate.from(of)
    var format = ofPattern.format(date)
    Log.e("TAG", "test 2--------->$format")
}

test 2 is the acquisition method provided by Android 8.0, which can get correct results

[catull]

JakeWarton actually referred you to https://github.com/ThreeTen/threetenbp/. This is the back-port of jsr-310 to Java 6+.

This is https://github.com/ThreeTen/threeten-extra. This is a "playground" to develop calendar models for Java 8+.

Look into timezone, see if that changes anything.

E.g.

fun test() {
    var hijrahDate = HijrahDate.now()
    var of1 = org.threeten.bp.LocalDate.of(2020, 2, 24)
    var date1 = HijrahDate.from(of1)
    var pattern = org.threeten.bp.format.DateTimeFormatter.ofPattern("MM/dd/yyyy")
    var s = date1.format(pattern.withZone(ZoneId.of("Asia/Riyadh")))

    Log.e("TAG", "test 1-------->$s")
}

Good luck. Can't help you with Android, I am afraid.

[lsgmkk]

no change.....

[jodastephen]

FWIW, I can't guarantee the quality of the Hijrah date code is as high as the ISO date code. This is because Oracle did most of the work on HijrahDate after the project went GPL licensed. As such, I'm unable to work on HijrahDate without polluting this codebase with GPL licensed code.