Re: Duration Calculation

[Joe <jfinlins@xxxxxxxxx>]

Just a couple of thoughts.

The SQL date math with DB2 is pretty slick.  If you're working with
dates that are already in the database it might just be easier to do
the calculation there, rather than in Java.  Something like DAYS(col1)
- DAYS(col2).  If you need the current time stamp you can select it as
a constant from sysibm/sysdummy1.  For more info on this approach you
may find this page useful:
http://www.ibm.com/developerworks/db2/library/techarticle/0211yip/0211yip3.html

So far as dealing with dates in Java, it's never been pretty.  To be
guaranteed that you're comparing apples to apples, especially when
doing date math, you should use a GregorianCalendar.  If you
instantiate two GregorianCalendars, one for each of the dates your
working with there are some methods provided by the Calendar interface
which should help you easily accomplish your task. Methods before(),
after(), equal(), and getTimeInMillis() look very promising.  If you
instantiate the GregorianCalendar objects correctly there shouldn't be
an issue with DST etc.

Check out the JavaDoc:
http://java.sun.com/j2se/1.4.2/docs/api/java/util/GregorianCalendar.html
http://java.sun.com/j2se/1.4.2/docs/api/java/util/Calendar.html
http://java.sun.com/j2se/1.4.2/docs/api/java/util/Date.html

Cheers!
Joe




On Jan 27, 2008 10:51 AM, Jon Paris <Jon.Paris@xxxxxxxxxxxxxx> wrote:
> Anyone got some Java code that will do a simple "days between two
> dates" calculation?  There are no times involved - just simple dates.
>
> I have Google'd for a solution but they all seem to involve mucking
> about with multiplication etc.  Most of them also seem to have at
> least one person pointing out that there will be problems with DST,
> or rounding, or ...
>
> Surely in this "all powerful" language there is an easy solution for
> such a simple business problem?  In RPG it is a simple %Diff - do I
> really need 20+ lines of Java to achieve the same thing?
>
> Jon Paris
>
> www.Partner400.com
> www.SystemiDeveloper.com
>
>
> --
> This is the Java Programming on and around the iSeries / AS400 (JAVA400-L) mailing list
> To post a message email: JAVA400-L@xxxxxxxxxxxx
> To subscribe, unsubscribe, or change list options,
> visit: http://lists.midrange.com/mailman/listinfo/java400-l
> or email: JAVA400-L-request@xxxxxxxxxxxx
> Before posting, please take a moment to review the archives
> at http://archive.midrange.com/java400-l.