Comments on: Counting the Days Between Two Java Dates using a Gregorian Calendar

By: Keyon

Keyon — Tue, 19 Jul 2011 18:21:51 +0000

At last, someone comes up with the “right” awnser!

By: Tasmine

Tasmine — Mon, 18 Jul 2011 17:47:45 +0000

Real brain power on dslpiay. Thanks for that answer!

By: Steve Neal

Steve Neal — Wed, 08 Jun 2011 15:41:38 +0000

Hi Michael,

Thanks for the comment. You are right, the example doesn’t take into account timezones or daylight saving time (DST). To cater for DST, you could add something like this:

long startTime = startCal.getTimeInMillis() + startCal.get(Calendar.DST_OFFSET);
to the startTime and endTime calculations.

I originally implemented this as a ’soft time’ requirement to show how long messages had been in an inbox, so the calculations didn’t need to be precise. I think the above suggestion should make this better now.

Steve.

By: Michael K

Michael K — Wed, 08 Jun 2011 09:05:54 +0000

No, the solution is incorrect since not all days have 24 hours. Think about daylight saving time.

By: Steve Neal

Steve Neal — Thu, 04 Mar 2010 17:46:50 +0000

Well spotted Bill

Looks like the calculations were right, just a terrible choice of variable names.

I’ve changed MILLISECONDS_IN_YEAR to MILLISECONDS_IN_DAY. It’s trying to count days after all, not years.

By: Bill

Bill — Thu, 04 Mar 2010 17:40:13 +0000

Errr, the number of milliseconds in the year isn’t as you have described it here. You are calculating the number of millis in a day.