Generify your List and Map and Set. Change the Iterator to a local variable; it may throw Exceptions if you have it as a field.
Why have you got so much code in the constructor?
Have you come across methods of the Character class which can tell whether a character is a letter, digit, etc? they may be easier for you to use.
If you are using f+"walkin.txt" can you add a File to a String? Will that code actually compile?
Will Object1.toString.compareTo(object2) compile? Because the compareTo method of String is parametrised to String it won't accept Object as a parameter.
The Vector class is a legacy class that has been retrofitted to implement the List interface.