日历中的月数不是恒定的？

Question

来自http://www.coderanch.com/t/381676/java/java/number-months-between-two-given,提到的一篇文章:

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);  
}  

日历中的月数不是恒定的吗？为什么？

Answer 1

是.在希伯来日历中,有几年有13个月(确切地说是19个中的7个).