question: private static void formatTimeZone ( Calendar cal , StringBuilder buf ) { TimeZone tz = cal . getTimeZone ( ) ; if ( tz == null ) return ; int offset ; if ( tz . inDaylightTime ( cal . getTime ( ) ) ) { offset = tz . getRawOffset ( ) + ( tz . useDaylightTime ( ) ? 3600000 : 0 ) ; } else { offset = tz . getRawOffset ( ) ; } if ( offset == 0 ) { buf . append ( 'Z' ) ; return ; } if ( offset >= 0 ) buf . append ( '+' ) ; else { buf . append ( '-' ) ; offset *= - 1 ; } offset /= 60 * 1000 ; formatTwoDigits ( offset / 60 , buf ) ; buf . append ( ':' ) ; formatTwoDigits ( offset % 60 , buf ) ; }
target:  formats time zone specifier. 