CODEWITHSUNDEEP
javacalendar
HJW
HJW

Reputation: 23443

The number of months in a Calendar is not constant?

From http://www.coderanch.com/t/381676/java/java/number-months-between-two-given, one post mentioned: 

public static int monthsBetween(Date minuend, Date subtrahend)  
{  
Calendar cal = Calendar.getInstance();  
// default will be Gregorian in US Locales  
cal.setTime(minuend);  
int minuendMonth =  cal.get(Calendar.MONTH);  
int minuendYear = cal.get(Calendar.YEAR);  
cal.setTime(subtrahend);  
int subtrahendMonth =  cal.get(Calendar.MONTH);  
int subtrahendYear = cal.get(Calendar.YEAR);  

// the following will work okay for Gregorian but will not  
// work correctly in a Calendar where the number of months   
// in a year is not constant  
return ((minuendYear - subtrahendYear) * cal.getMaximum(Calendar.MONTH)) +    
(minuendMonth - subtrahendMonth);  
}

Is it true that the number of months in a Calendar is not constant? And why?

Upvotes: 4

Views: 2041

Answers (2)

irreputable
irreputable

Reputation: 45443

It is funny that, month comes from moon. A lunar calendar usually sync days with moon phases, so that, for example, day 15 of any month is always a full moon day.

The problem is a solar year is not exactly 12 moon cycles. So a lunar calendar must have "leap months".

Upvotes: -1

MByD
MByD

Reputation: 137382

Yes. In the hebrew calendar, there are several years with 13 months (7 out of 19 to be exact).

Upvotes: 9

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