Re: Timezones and versions of Java
loial wrote:
I am trying to convert BST times to EST.
What time zones do you mean here? Bangladesh Standard Time? British Summer
Time? Eastern Standard Time in the Caribbean?
Neither "EST" nor "BST" is a standard time-zone name.
Have you considered reading the documentation?
The following code correctly returns a difference of 5 hours between
the 2 times when run under Java 1.5. :
Local Offset 3600000
EST Offset -14400000
EST time Tue May 04 07:48:18 2010
You do realize that Eastern Time is not "EST" on May 4 anywhere other than
Australia, right? Any other jurisdiction that uses "EST" as an abbreviation
is on Summer Time on that date. Therefore you must be referring to Australian
time, but that's the wrong offset for that zone.
Please clarify.
In any case, there's nothing correct in what you show here. Why do you say
this is a correct return?
BST time Tue May 04 12:48:18 2010
Does Bangladesh have Daylight Saving Time?
However if run under Java 1.6 (on the same machine), it returns a time
difference of 6 hours :
Local Offset 3600000
EST Offset -18000000
EST time Tue May 04 06:48:18 2010
BST time Tue May 04 12:48:18 2010
Do I need to do something different in Java 1.6?.
Maybe give it the right time zone?
You do realize that Eastern Standard Time in the U.S. is -18000000
milliseconds offset from UTC, right? So if "EST" is "America/New_York" (and,
of course, not Daylight Saving Time), then this display is correct.
What makes you think that it is not correct?
Platform is linux [sic].
class testtz {
Class names should start with an upper-case letter.
public static void main(String[] args) {
Date date = null;
Why do you set the date to 'null'? It's unnecessary and potentially harmful;
it certainly is harmful in the code you show here.
SimpleDateFormat dateFormat = new
SimpleDateFormat("yyyyMMddHHmmss");
try {
date = dateFormat.parse("20100504124818");
Here you throw away that 'null' value that you shouldn't have initialized.
}
catch(ParseException pe) {
System.out.println("Error");
}
TimeZone tz1 = TimeZone.getDefault();
If you're in the Northern Hemisphere in most jurisdictions, you will not get
"EST" from this on May 4.
long localOffset = tz1.getOffset(date.getTime());
System.out.println("Local Offset " + localOffset);
TimeZone tz2 = TimeZone.getTimeZone("EST");
long remoteOffset = tz2.getOffset(date.getTime());
System.out.println("EST Offset " + remoteOffset);
Date dateToPutInDB = new Date(date.getTime() - localOffset +
remoteOffse;
System.out.println("EST time " + dateToPutInDB)
System.out.println("BST time " + date);
}
}
<http://download.oracle.com/javase/6/docs/api/java/util/TimeZone.html>
"Three-letter time zone IDs
"For compatibility with JDK 1.1.x, some other three-letter time zone IDs (such
as "PST", "CTT", "AST") are also supported. However, their use is deprecated
because the same abbreviation is often used for multiple time zones (for
example, "CST" could be U.S. "Central Standard Time" and "China Standard
Time"), and the Java platform can then only recognize one of them."
Have you considered reading the documentation?
RTFM.
RTFM.
RTFM.
--
Lew
RTFM.