question: public static String toHexString ( byte [ ] bytes ) { if ( bytes == null ) return "" ; int i ; String ret = "" ; String tmp ; for ( i = 0 ; i < bytes . length ; i ++ ) { if ( i > 0 ) ret += ":" ; tmp = Integer . toHexString ( U8 . f ( bytes [ i ] ) ) ; if ( tmp . length ( ) == 1 ) ret += "0" ; ret += tmp ; } return ret ; }
target:  Convert a string of bytes to a ':' separated hex string