java - Joda时间(Java): Hijri to Gregorian conversion inaccurate?

Question

我目前正在实现一个日历转换器，根据回历输入日期和时间，使用 JodaTime 库输出相应的公历日期和时间。然而，相应的公历时间并不准确。无论我在同一天输入哪个回历时间，生成的公历日期都是相同的。考虑到每个回历日跨越两个公历日，从日落到日落，这似乎很奇怪，如本答案 ( https://islam.stackexchange.com/questions/71850/can-a-day-in-the-gregorian-calendar-correspond-to-two-different-days-in-the-isla ) 中所述。

例如，下面是从回历日期时间(当前日期，可以指定一天中的不同时间)转换为相应的公历日期时间的代码:

Chronology iso = ISOChronology.getInstanceUTC();
Chronology hijri = IslamicChronology.getInstanceUTC();

DateTime currentDate = DateTime.now();
int year = currentDate.getYear();
int month = currentDate.getMonthOfYear();
int day = currentDate.getDayOfMonth();

int customHr = 23;
int customMin = 59;
int customSec = 59;

DateTime todayIso = new DateTime(year, month, day, customHr, customMin, customSec, 0, iso);
LocalDateTime todayHijri = new LocalDateTime(todayIso, hijri);
System.out.println(todayHijri.toString());

结果如下:

Hijri DateTime Input: 8/24/2021 at final second (23:59)
Gregorian DateTime Output: 1443-01-15T23:59:59.000

Hijri DateTime Input: 8/24/2021 at first second (0:01)
Gregorian DateTime Output: 1443-01-15T00:00:01.000

但是，当我运行这段从公历日期时间转换为回历日期时间的代码时:

Chronology hijri = IslamicChronology.getInstanceUTC();

int customHour = 0;
int customMin = 0;
int customSec = 1;

DateTime todayIso = new DateTime(2021, 8, 24, customHour, customMin, customSec);
LocalDateTime todayHijri = new LocalDateTime(todayIso, hijri);
System.out.println(todayHijri); 

这些是我使用公历到回历转换的输出作为输入得到的结果。正如您所看到的，输出的回历日期时间与回历到公历转换中的输入回历日期时间不同，这意味着出现了问题。

Gregorian DateTime Input: 8-24-2021 at 0:01
Hijri DateTime Output: 1443-01-15T07:00:01.000

Gregorian DateTime Input: 8-24-2021 at 23:59:59
Hijri DateTime Output: 1443-01-16T06:59:59.000

Answer 1

来自:http://joda-time.sourceforge.net/cal_islamic.html

A day in the Islamic calendar begins at sunset on the previous 'day'. Joda-Time does not model this, thus times and date rollover follow standard ISO definitions, in other words starting at midnight

如Joda-Time is in maintenance ,

参见:How to convert from Hijri Date to Georgian Date and vice versa用于选项。