How to get leap months in chinese calendar

[dearming623]

The library works very well.

Can you provide a method to get the leap month of the year and the number of days of the leap month.

[MenoData]

For length of month in days (leap month or not), just look at the method lengthOfMonth() in the super class EastAsianCalendar. Another standardized (but more complicated) approach would be: chineseCalendar.getMaximum(ChineseCalendar.DAY_OF_MONTH).

About finding leap month in a given year, this is more complicated because there is no simple algorithmic formula to find it. It happens all 2-3 years once and can match almost every month to be doubled. At least you can easily determine if a given year contains a leap month at all by calling the method isLeapYear(). So a kind of search iterating over every month in given leap year would give the leap month in question. Something like (untested):

ChineseCalendar chineseCalendar = ChineseCalendar.ofNewYear(2020);
EastAsianMonth m;

while (
  !(m = chineseCalendar.getMonth()).isLeap() 
  && (chineseCalendar.getInt(CommonElements.RELATED_GREGORIAN_YEAR) == 2020)
) {
  chineseCalendar = chineseCalendar.plus(1, ChineseCalendar.Unit.MONTHS);
}

if (m.isLeap()) {
  System.out.println("Leap month found in 2020:" + m);
}

Good luck, By the way, I am offline for the next two weeks (far away from phone and internet in my holidays).

[MenoData]

I have now added two extra methods to the super class EastAsianCalendar with following signatures:

// Query for finding a leap month within the current calendar year
public Optional<EastAsianMonth> findLeapMonth()

// Moving the current date to begin of next leap month
public D withBeginOfNextLeapMonth()