It is a bug:
run happyNewYear(1964)
output:
TimeZone:Atlantic/Reykjavik
date in yearFromDate : 1964-01-01 00:00:00 Etc/GMT
yearFromDate : 1963
package some.packagename;
import java.util.GregorianCalendar;
import java.util.TimeZone;
import com.webobjects.foundation.NSTimeZone;
import com.webobjects.foundation.NSTimestamp;
public class HappyNewYear {
static {
TimeZone.setDefault(TimeZone.getTimeZone("Atlantic/Reykjavik"));
NSTimeZone.setDefault(TimeZone.getTimeZone("Atlantic/Reykjavik"));
}
public static int yearFromDate(NSTimestamp date) {
if (null == date) {
return 0;
}
System.out.println("TimeZone:" + TimeZone.getDefault().getID());
GregorianCalendar cal = new GregorianCalendar();
cal.setTime(date);
System.out.println("date in yearFromDate : " + date);
int result = cal.get(GregorianCalendar.YEAR);
System.out.println("yearFromDate : " + result);
return result;
}
public static void happyNewYear(int year) {
NSTimestamp newYear = new NSTimestamp(year, 1, 1, 0, 0, 0, null);
yearFromDate(newYear);
}
}
-----Original Message-----
From: Ken Anderson [mailto:[email protected]]
Sent: Fri 09-Jan-09 15:23
To: Lachlan Deck
Cc: Barði Einarsson; WebObjects-Dev Mailing List List
Subject: Re: Bug ID 6342679: NSTimestamp Happy New Year Bug
Bardi,
I think the most important thing to understand about how dates are
moved around is that the value is always GMT based. Timezones are
there for convenience...
For instance, when you create a new timestamp with a timezone, the
timezone is used to adjust the date/time you sent in to GMT and the
GMT value is stored. When formatting a date or extracting day/month/
year from GregorianCalendar, the timezone is used WHEN FORMATTING THE
RESULT.
If you work with these tenets, things will hopefully be easier.
Ken
On Jan 8, 2009, at 6:54 PM, Lachlan Deck wrote:
> On 09/01/2009, at 3:10 AM, Ken Anderson wrote:
>
>> I do exactly what you're doing all the time, and I do not have the
>> issue you're experiencing. One thing I do at the beginning of my
>> WOApplication subclass is this:
>>
>> TimeZone.setDefault(TimeZone.getTimeZone("GMT"));
>> NSTimeZone.setDefault(TimeZone.getTimeZone("GMT"));
>>
>> This will make sure that you're really working in GMT across the
>> board. Can you do the above and try your tests again?
>
> Yep.
>
>>> Behaves correctly - no way
>
> Yes way :-)
>
>>> NSTimestamp reports a timezone which is not used by
>>> GregorianCalendar ??
>
> GregorianCalendar does *not* change its timezone based on the date
> passed to it. You are responsible for determining that. That's
> nothing to do with NSTimestamp.
>
>>> This is a difficult bug.
>
> Just more a misunderstanding on your part.
>
> with regards,
> --
>
> Lachlan Deck
>
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