Comments on: Find the Difference Between two Java Dates (Calendars)

By: Dragan

Dragan — Sat, 06 Dec 2008 18:50:58 +0000

Thanks for posting this online. It really helped me. I just can’t believe there is no such util included with standard jdk.

By: Naren

Naren — Sat, 08 Mar 2008 15:41:46 +0000

Hi
I think you should use


unitEstimates.put(Calendar.MONTH, 1000l * 60 * 60 * 24 * 28);

instead of


unitEstimates.put(Calendar.MONTH, 1000l * 60 * 60 * 24 * 30);

in the differenceGetUnitEstimates() method
For example as the code stands today – it returns the difference in months between Feb 7, 2008 and Mar 7, 2008 as 0(zero)
This is because Feb has only 29 days and the code snippet in difference(Calendar c1, Calendar c2, int unit)


long increment = (long) Math.floor((double) difference / (double) unitEstimate);

returns zero as the increment as a result
The while loop skips over an zero increment value.


while (increment > 0) {

The fix I suggested was based on the observation that every month has 28 days (leap year february included) and the basic logic of finding the number of months elapsed based on the increments still is a fundamentally strong idea
Let me know what you think. I have done some testing on this as well and it works.

By: Stucco

Stucco — Thu, 06 Mar 2008 05:19:56 +0000

Updated the code 3/5/2008 to fix a bug where the estimated time was greater than the actual time passed, yet the time passed was sufficient to be a single unit. For example Feb 1st to March 1st. Thank you Tim for catching this bug.

By: naren

naren — Sun, 21 Oct 2007 21:48:41 +0000

neat idea to get over those leap year issues!