@Override public DateInterval toInterval( DateTimeUnit dateTimeUnit, DateIntervalType type, int offset, int length ) { switch ( type ) { case ISO8601_YEAR: return toYearIsoInterval( dateTimeUnit, offset, length ); case ISO8601_MONTH: return toMonthIsoInterval( dateTimeUnit, offset, length ); case ISO8601_WEEK: return toWeekIsoInterval( dateTimeUnit, offset, length ); case ISO8601_DAY: return toDayIsoInterval( dateTimeUnit, offset, length ); } return null; }