Question

For example:
Data Given :

1. Year-2010,
   Month-2,
   Fortnight-1

2. Current date

How do I get the difference in terms of number of fortnights between the two given dates?

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This is what I figured out and its working fine…

Calendar c= Calendar.getInstance();
int year = 2011;
int month = 6;
int fortnight = 1;
int noofmonths=(c.get(Calendar.YEAR)-year)*12;  
noofmonths=(noofmonths+((12-(month-1)+(c.get(Calendar.MONTH)-12)))-1)*2;
int nooffortnights=noofmonths+((2-(fortnight-1)+((c.get(Calendar.DAY_OF_MONTH)<15?1:2)-2)))-1;
System.out.println("nooffortnights : "+nooffortnights); //outputs 5

Answer 1

This depends on your definition of fortnights. If we are literal minded then a fortnight is defined as 14 days, so compute the number of days and divide by 14, job done.

I suspect that in your case we are actually using a special business calendar, where fortnights are a subdivision of quarters and hence there are some special cases – a year doesn’t exactly divide into fortnights and perhaps the business year does not start on Jan 1st? So somewhere there will be a definitive list of the dates of the start of each fortnight in a year.

Let’s suppose that the fortnight definitions have

 17th Nov - 1st Dec
 2nd Dec - 15th Dec
 16th Dec - 31st Dec   (note this is 15 days long)

Now what’s the definition on how many fortnights from 17th Nov to 16th Dec? I guess 2. From 19th Nov to 16th Dec? I have no idea what answer you would expect.

So first, get really clear what the business requirements are. I’d be surprised is you will find off-the-shelf date packages that understand fortnights, but even if you do you need to check very carefully that they give the answers you need.