code: public static Calendar getCalendarInstance(final Date date) {
          Calendar instance;
          if (date instanceof DateTime) {
              final DateTime dateTime = (DateTime) date;
              if (dateTime.getTimeZone() != null) {
                  instance = Calendar.getInstance(dateTime.getTimeZone());
              }
              else if (dateTime.isUtc()) {
                  instance = Calendar.getInstance(TimeZones.getUtcTimeZone());
              }
              else {
              	// a date-time without a timezone but not UTC is floating
                  instance = Calendar.getInstance();
              }
          }
          else {
              instance = Calendar.getInstance(TimeZones.getDateTimeZone());
          }
          return instance;
      }
docs: Returns an instance of <code>java.util.Calendar</code> that is suitably
  initialised for working with the specified date.
  @param date a date instance
  @return a <code>java.util.Calendar</code>