question: public static String hexCodeString ( byte [ ] code ) { if ( code == null ) { return "" ; } else { StringBuilder sb = new StringBuilder ( code . length * 2 ) ; for ( int b : code ) { String hex = Integer . toHexString ( b & 0xff ) ; if ( hex . length ( ) == 1 ) { sb . append ( '0' ) ; } sb . append ( hex ) ; } return sb . toString ( ) ; } }
target:  Formats a byte array as a string of hex digits.