question: private static String toHex ( byte [ ] array ) { BigInteger bi = new BigInteger ( 1 , array ) ; String hex = bi . toString ( 16 ) ; int paddingLength = ( array . length * 2 ) - hex . length ( ) ; if ( paddingLength > 0 ) return String . format ( "%0" + paddingLength + "d" , 0 ) + hex ; else return hex ; }
target:  Converts a byte array into a hexadecimal string.