Java – Convert a string to GregorianCalendar

calendarjavatimezone

I have a string from an email header, like Date: Mon, 27 Oct 2008 08:33:29 -0700. What I need is an instance of GregorianCalendar, that will represent the same moment. As easy as that — how do I do it?

And for the fastest ones — this is not going to work properly:

SimpleDateFormat format = ... // whatever you want
Date date = format.parse(myString)
GregorianCalendar calendar = new GregorianCalendar();
calendar.setTime(date)

because it will normalize the timezone to UTC (or your local machine time, depending on Java version). What I need is calendar.getTimeZone().getRawOffset() to return -7 * milisInAnHour.

Best Solution

I'd recommend looking into the Joda Time library, if that's an option. I'm normally against using a third-party library when the core platform provides similar functionality, but I made this an exception because the author of Joda Time is also behind JSR310, and Joda Time is basically going to be rolled into Java 7 eventually.

http://joda-time.sourceforge.net/

So anyway, if Joda Time is an option, something like this should work:

DateTimeFormatter formatter =
    DateTimeFormat.forPattern("your pattern").withOffsetParsed();
DateTime dateTime = formatter.parseDateTime("your input");
GregorianCalendar cal = dateTime.toGregorianCalendar();

I hope this helps.