Time Zone Offset - Date Format question

Question

I'm wondering if any one knows how to display the time zone offset of a date in the following format "[+-]HH:mm." More so... I need the date/time in the ISO 8601 format "yyyy-MM-dd'T'HH:mm:ss[+-]HH:mm", where the last [+-]HH:mm is the hour representation of the offset. Here's some sample code...
SimpleDateFormat sdf1 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
Calendar rightnow= Calendar.getInstance();
// So if system date/time is February 14, 2002 at 1:15:00 PM EST, this would produce "2002-02-14T13:15:00"
System.out.println("Current Datetime" + sdf1.format rightnow.getTime());
How can I get the timezone offset appended to my output in a [+-]HH:mm format. So, the above date needs to look like "2002-02-14T13:15:00-05:00". I can get the offset in milliseconds by doing the following:
int offset1 = rightnow.get(rightnow.ZONE_OFFSET) + rightnow.get(rightnow.DST_OFFSET);
But how can you get this representation into the [+-]HH:mm format?
thanks in advance,
stophman

Answer 1

Try something like this:import java.text.* ;
import java.util.* ;
static public String formatISO8601(Calendar cal) {
     * create ISO 8601 formatter for Calendar objects
    MessageFormat iso8601 = new MessageFormat("{0,time}{1,number,+00;-00}:{2,number,00}") ;
    // need to shove a date formatter that is cognizant of the
    // calendar's time zone into the message formatter
    DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss") ;
    df.setTimeZone(cal.getTimeZone()) ;
    iso8601.setFormat(0, df) ;
     * calculate the time zone offset from UTC in hours and minutes at the current time
    long zoneOff = cal.get(Calendar.ZONE_OFFSET) + cal.get(Calendar.DST_OFFSET) ;
    zoneOff /= 60000L ;  // in minutes
    int zoneHrs = (int) (zoneOff / 60L) ;
    int zoneMins = (int) (zoneOff % 60L) ;
    if (zoneMins < 0) zoneMins = -zoneMins ;
    return (iso8601.format(new Object[] {
                                cal.getTime(),
                                new Integer(zoneHrs),
                                new Integer(zoneMins)
}