The whole way this class is set out is illogical. It creates a set of instance methods and then treats them like static methods. If we are going to use instance methods we may as well make use of their characteristics. e.g.

1. initialising private class variables which are common to more than one method.
2. instantiating them in a constructor or method with the this keyword

That way, the instantiated object can be passed about all the methods in the class. Otherwise there's not much point having instance methods and they may as well be static. In this case though I think instance methods are appropriate but they are just not getting used in an optimal way.