Question

Another similar question:
When calling a method (from separate class) that returns a value which is derived from another class (from within the separate class). Do we need to instantiate the variables of derived class in that calling method?

Answer 1

If you are calling a method in another class, the variables already are instantiated. In order to call said method, you must have either a) constructed a new object i.e

Object myObject = new Object();
myObject.myMethod();

or b) the method is static, which means it is instantiated already and you can call it as

Object.myMethod();

in either case, the variables used by the class are instantiated upon construction, and those used locally by the function are allocated once the function is called.