Exercise 15 finished
Exercise 15: (2) Create a class with a non-default constructor (one with arguments) and
no default constructor (no "no-arg" constructor). Create a second class that has a method
that returns a reference to an object of the first class. Create the object that you return by
making an anonymous inner class that inherits from the first class
* 
* for inner class extends from class have constructor, inner class cannot define its own constructor 
* inside the class fields, fields can be inited by {} and upcast can work on the inner class. No downcast here.
* A details: parameter specific with final must distinct between fields defined in class, if they have same name,
* compiler will give the native fields a wrong pointer