Output RFC 3339 Timestamp in Java

Question

I want to output a timestamp with a PST offset (e.g., 2008-11-13T13:23:30-08:00). java.util.SimpleDateFormat does not seem to output timezone offsets in the hour:minute format, it excludes the colon. Is there a simple way to get that timestamp in Java?

// I want 2008-11-13T12:23:30-08:00
String timestamp = new SimpleDateFormat("yyyy-MM-dd'T'h:m:ssZ").format(new Date());
System.out.println(timestamp); 
// prints "2008-11-13T12:23:30-0800" See the difference?

Also, SimpleDateFormat cannot properly parse the example above. It throws a ParseException.

// Throws a ParseException
new SimpleDateFormat("yyyy-MM-dd'T'h:m:ssZ").parse("2008-11-13T13:23:30-08:00")

Answer 1

Starting in Java 7, there's the X pattern string for ISO8601 time zone. For strings in the format you describe, use XXX. See the documentation.

Sample:

System.out.println(new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssXXX")
        .format(new Date()));

Result:

2014-03-31T14:11:29+02:00

Answer 2

Check out the Joda Time package. They make RFC 3339 date formatting a lot easier.

Joda Example:

DateTime dt = new DateTime(2011,1,2,12,45,0,0, DateTimeZone.UTC);
DateTimeFormatter fmt = ISODateTimeFormat.dateTime();
String outRfc = fmt.print(dt);

Answer 3

From the "get it done dept," one solution is to use regexes to fix up the string after SimpleDateFormat has completed. Something like s/(\d{2})(\d{2})$/$1:$2/ in Perl.

If you are even remotely interested in this, I will edit this response with the working Java code.

But, yeah. I am hitting this problem too. RFC3339, I'm looking at you!

EDIT:

This works for me

// As a private class member
private SimpleDateFormat rfc3339 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");

String toRFC3339(Date d)
{
   return rfc3339.format(d).replaceAll("(\\d\\d)(\\d\\d)$", "$1:$2");
}