Don't use == to compare reference types for equality. Don't say == true (or == false). Those uses of == are prone to errors, the first because they are liable to return false when you want true, the second in case you write = by mistake.
You may be able to reduce that enormous block of if-elses to
Main.alpha = charset.equals("Alphanumeric etc etc");
Main.numeric = charset.equals("Numbers etc etc"); etc
You should use get and set methods rather than public attributes for those booleans.
For reasons explained
here, avoid abbreviations like "coz".