How to interpret the these time stamps?

Question

I'm trying to parse the time stamps written in some xml files. Most to the time time stamps are something like 2009-07-22-07:00 but some times I find them something like 2009-07-22Z or 2009-07-22z. Kindly help me how to interpret these Zs and how to parse them. I thing these z or Z is related to the time zone. Any workarounds to parse them just like the typical time stamps?

Answer 1

The Z means Zulu. You're correct, it does represent the time zone - specifically UTC.

Answer 2

You're correct. The trailing character refers to the timezone.

The Z refers to the "Zulu" timezone, which is just shorthand for the UTC (or GMT) timezone.

You may also see a trailing +X or -X. These refer to the GMT offset for the timestamp. e.g. 2002-05-30+06:00 indicates that the time is GMT + 6 hours and zero minutes.

Answer 3

XML uses ISO8601 time formats, so that standard is the first place to look for all things timerelated in XML.

Answer 4

To add to fvu's answer: Java unfortunately does not have any built-in method to parse (or format ISO8601 date and time format, and even more unfortunately it is not (easily) possible to parse ISO8601 dates with java.text.SimpleDateFormat.

The well-known and popular Joda Time library does have good support for ISO8601 dates and times.

Edit: Since Java 5, there are classes in the standard API to parse and format dates and times in the standard format often used in XML documents. To parse a date:

import java.util.Calendar;
import java.util.Date;
import javax.xml.datatype.DatatypeFactory;
import javax.xml.datatype.XMLGregorianCalendar;

// ...

String dateString = "..."; // wherever you get this from
XMLGregorianCalendar xcal = DatatypeFactory.newInstance().newXMLGregorianCalendar(dateString);

Calendar cal = xcal.toGregorianCalendar();
Date date = cal.getTime();

Likewise there are methods to format dates into strings. See the API documentation of those classes for details.