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Poonam posted an Question
January 23, 2020 • 02:38 am 15 points
  • UGC NET
  • Computer Science & Applications

Consider the following code Px = new Q(); Qy = new Q0: Pz = new Q); x. f (1):((P) y). f (1); z.f(1); The output is (A) 121 (B) (D) 2 1 1 (C) 212 2 22

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    Bajrang best-answer

    ans is D 222 this is polymorphism  Superclass object = new subclass(); object created for subclass referenced by a superclass  when anything invoked using this object (THIS IS IMPORTANT)  All the methods of superclass can be invoked which are not in subclass  AND when a method is invoked which is in both (overridden) the SUBCLASS Method will be called!!  Additional info-->  superclass to subclass requires EXPLICIT CASTING  subclass to superclass doesn't require explicit casting (although no problem if used) Inheritance will make sure every function in parent class P is also a part of Q. But since Q has overridden the function f, Q's definition of function f will be used whenever an object of type Q is used to call f. Dynamic binding determines the type of the object at run-time and not compile time. Refer  http://www.javatpoint.com/static-binding-and-dynamic-binding Looking at the pseudo code, in all the cases x.f(1), ((P) y), z.f(1), the objects are of type Q, hence function f from child class will be used. And since the definition of function f is present in parent class as well there wont be any exceptions.

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