P8W

Who knew the ISO had a duration format?

import org.joda.time.DateMidnight;
import org.joda.time.Weeks;
public class DaysSinceRelease {
    public static void main(String[] args) {
        DateMidnight lastRelease = new DateMidnight(2010, 10, 17);
        DateMidnight today = new DateMidnight();
        Weeks weeks = Weeks.weeksBetween(lastRelease, today);
        System.out.format("Weeks since last release: %s\n", weeks);
    }
}

Weeks since last release: P8W