Finding Date Difference

Question

What's the efficient way of finding say if a date is 5 days earlier than another day? Do I need to parse both days using a particular SimpleDateFormat first before I compare?

5 calendar days? 5 business days? – David Koelle Dec 07 '09 at 18:23 — David Koelle, Dec 07 '09 at 18:23

score 12 · Answer 1 · answered Dec 07 '09 at 18:08

12

The best Java date time API is Joda Time. It makes these tasks, and others, much easier than using the standard API.

answered Dec 07 '09 at 18:08

Joel

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score 1 · Answer 2 · answered Dec 07 '09 at 18:07

Most quickly, but least accurately, you might just put both into a java.util.Date, getTime() on both, and divide the difference by the number of milliseconds in a day.

You could make it a bit more accurate by creating two Calendar objects, and work with those.

If you really want to solve this well, and have a good bit of time on your hands, look at Joda Time.

score 1 · Answer 3 · answered Dec 07 '09 at 18:08

1

The Calendar interface has some nice methods, including before, after, and equals.

answered Dec 07 '09 at 18:08

rynmrtn

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The whole API is however fairly epic fail: http://stackoverflow.com/questions/1697215/what-is-your-favourite-java-api-annoyance/1697229#1697229 See for example the calendar example and the jodatime example in this topic: http://stackoverflow.com/questions/567659/calculate-elapsed-time-in-java-groovy/1776721#1776721 – BalusC Dec 07 '09 at 18:44

score 0 · Answer 4 · answered Dec 07 '09 at 18:05

0

http://www.java2s.com/Code/Java/Development-Class/DateDiffcomputethedifferencebetweentwodates.htm

answered Dec 07 '09 at 18:05

Peter

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Dónal · Answer 5 · 2009-12-07T19:52:53.707

0

Date date1 = // whatever
Date date2 = // whatever

Long fiveDaysInMilliseconds = 1000 * 60 * 60 * 24 * 5    
boolean moreThan5Days = Math.abs(date1.getTime() - date2.getTime()) > fiveDaysInMilliseconds

edited Dec 07 '09 at 19:52

answered Dec 07 '09 at 18:16

Dónal

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You can't just say `date1 - date2`. – Michael Myers Dec 07 '09 at 18:47
Thanks, I forgot the calls to 'getTime()' - I've been working with Groovy recently which overloads the '-' operator so you can say `date1 - date2` – Dónal Dec 07 '09 at 19:54

score 0 · Answer 6 · edited Dec 07 '09 at 18:22

0

You can do

Long DAY_IN_MILLIS = 86400000;

if((dateA - dateB) > DAY_IN_MILLIS * 5) {
    // dateA is more than 5 days older than dateB
}

edited Dec 07 '09 at 18:22

Dónal

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answered Dec 07 '09 at 18:19

MattGrommes

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score 0 · Answer 7 · answered Dec 07 '09 at 20:19

If you need to ignore the time of the dates, you can do something like

    public static boolean compare5days(Date date, Date another) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(another);
        cal.add(Calendar.DATE, -5);

        // clear time 
        cal.set(Calendar.HOUR_OF_DAY, 0);
        cal.set(Calendar.MINUTE, 0);
        cal.set(Calendar.SECOND, 0);
        cal.set(Calendar.MILLISECOND, 0);

        return date.before(cal.getTime());
    }

score -1 · Accepted Answer · answered Dec 07 '09 at 18:05

-1

days = (date2.getTime() - date1.getTime())/86400000L

answered Dec 07 '09 at 18:05

Reverend Gonzo

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This is maybe the most efficient, but this does not take DST into account. – BalusC Dec 07 '09 at 18:21
1

-1 That's wrong unless the Date instances were derived from UTC times. – sleske Aug 30 '10 at 13:27

score -1 · Answer 9 · answered Dec 07 '09 at 18:56

-1

days = (date2.getTime() - date1.getTime())

answered Dec 07 '09 at 18:56

user226593

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This is not correct since java.util.Date.getTime() returns number of milliseconds. So this difference gives number of milliseconds between date1 and date2. – wheleph Dec 07 '09 at 19:37

Finding Date Difference

9 Answers9