Re: Duration Calculation

[Don Yantzi <yantzi@xxxxxxxxxx>]

Hi Jon,

I was quite surprised to find out Java doesn't have a simple method for 
calculating this (we don't do much date manipulation in the RSE). The Java 
classes all store time as the number of milliseconds since EPOCH. I guess 
this makes it easier to handle timezones and DST stuff. So one way to do 
this would be to:

GregorianCalendar date2 = new GregorianCalendar(2000, 01, 15);
GregorianCalendar date1 = new GregorianCalendar(2008, 02, 21);

long diff;
if (date1.before(date2)) 
        diff = date2.getTimeInMillis() - date1.getTimeInMillis();
else
        diff = date1.getTimeInMillis() - date2.getTimeInMillis();
 
diff = diff / (1000 * 60 * 60 * 24);  // convert from diff in milliseconds 
to days
 
System.out.println(diff)

There might be a better way. And you might want to test this bit of code 
before using it in product [standard IBM code sample disclaimer goes 
here].

Don Yantzi
Technical Lead
WebSphere Development Studio Client for iSeries
IBM Toronto Lab





Jon Paris <Jon.Paris@xxxxxxxxxxxxxx> 
Sent by: java400-l-bounces@xxxxxxxxxxxx
01/27/2008 01:44 PM
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Java Programming on and around the iSeries / AS400 
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Re: Duration Calculation







On 27-Jan-08, at 1:00 PM, java400-l-request@xxxxxxxxxxxx wrote:

> You can load it into a java.util.Date, extract the corresponding 
> number
> of milliseconds since 1970.01.01, and you can then take the difference
> and round down to number of days.

This is part of the current problem - the date related classes seem 
to be trying to deal with Daylight Savings Time or something and when 
your dates cross the changeover point the results are inaccurate.

Besides - doesn't it strike you as thoroughly silly that one should 
even have to contemplate "playing" with milliseconds to get a count 
of a number of days!  It is insane that such steps should be required 
in a so-called "modern" language.

Buying a package to solve a basic language deficiency just sticks in 
my craw I'm afraid.

Jon Paris

www.Partner400.com
www.SystemiDeveloper.com