question: public static String generateCode ( int codeSize ) { Random sr = new Random ( ) ; char [ ] randomChars = new char [ codeSize ] ; randomChars [ 0 ] = letters . charAt ( sr . nextInt ( letters . length ( ) ) ) ; for ( int i = 1 ; i < codeSize ; ++ i ) { randomChars [ i ] = ALLOWED_CHARS . charAt ( sr . nextInt ( NUMBER_OF_CODEPOINTS ) ) ; } return new String ( randomChars ) ; }
target:  Generates a pseudo random string using the allowed characters.