CODEWITHSUNDEEP
javadatetimetimezoneutcjodatime
ovdsrn
ovdsrn

Reputation: 793

Convert time represented as String containing timezone names ('z') to UTC time

I want to convert Strings like "20000603163334 GST" or "20000603163334 -0300" to UTC time. The problem is that time zones in my strings can be 'general time zones', I mean they can be strings as CET, GST etc. etc. And I don't know how to convert these ones.

Because of these string time zones I can not use Joda Time's DateTimeFormat.forPattern("yyyyMMddhhmmss z").withZone(DateTimeZone.UTC);, because according to the documentation: "Time zone names ('z') cannot be parsed".

So, one question I have is if you know a method to go around this limitation in Joda Time? I would prefer to use Joda Time, if possible, instead of the standard Java API.

Another in which I thought I can solve this problem with time zone's names is to use the Java's SimpleDateFormat. So I make something like:

SimpleDateFormat f = new SimpleDateFormat("yyyyMMddhhmmss z");
//f.setTimeZone(TimeZone.getTimeZone("UTC"));
f.setCalendar(new GregorianCalendar(TimeZone.getTimeZone("UTC")));
Date time = f.parse("20000603163334 GST");

The SimpleDateFormat parses the String (I don't care here about the problem that there are multiple time zones with the same name - what this class parses it's good for me).

The problem is that I don't know how to convert it from here to UTC. How can I do this?

The fact that I set the f's time zone to UTC (in both the two ways from above) doesn't help. I hope someone can help me fix this, I read a lot of questions and answers on this theme here, on stackoverflow, but I haven't found a solution yet.

Upvotes: 3

Views: 10017

Answers (1)

Joe
Joe

Reputation: 3059

I found two solutions to your problem. The first was to set the default time zone to UTC:

TimeZone.setDefault(TimeZone.getTimeZone("UTC"));

I'm not sure what other side effect this might have.

The second solution I found was to use a different SimpleDateFormat for output.

SimpleDateFormat f = new SimpleDateFormat("yyyyMMddhhmmss z");
f.setTimeZone(TimeZone.getTimeZone("UTC"));
Date time = f.parse("20000603163334 GST");
System.out.println(time);
System.out.println("(yyyyMMddhhmmss z):  " + f.format(time));
    
SimpleDateFormat utc = new SimpleDateFormat("yyyyMMddhhmmss z");
utc.setTimeZone(TimeZone.getTimeZone("UTC"));
    
System.out.println("(yyyyMMddhhmmss z):  " + utc.format(time));

Using two SimpleDateFormat objects allowed the output to be put in UTC Time. Here is the output from running this code:

Sat Jun 03 08:33:34 EDT 2000

(yyyyMMddhhmmss z): 20000603043334 GST

(yyyyMMddhhmmss z): 20000603123334 UTC

Here may be the reason why Joda does not support 3 letter zone ids. This is from the TimeZone ( http://download.oracle.com/javase/6/docs/api/java/util/TimeZone.html ) JavaDoc. As far as Joda goes, I didn't see a workaround, but I'm not very familiar with that library.

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.

Upvotes: 6

Related Questions