I was presented with this question in an end of module open book exam today and found myself lost. I was reading Head first Javaand both definitions seemed to be exactly the same. I was just wondering what the MAIN difference was for my own piece of mind. I know there are a number of … Read more
Consider the code : #include <stdio.h> class Base { public: virtual void gogo(int a){ printf(” Base :: gogo (int) \n”); }; virtual void gogo(int* a){ printf(” Base :: gogo (int*) \n”); }; }; class Derived : public Base{ public: virtual void gogo(int* a){ printf(” Derived :: gogo (int*) \n”); }; }; int main(){ Derived obj; … Read more
In terms of Java, when someone asks: what is polymorphism? Would overloading or overriding be an acceptable answer? I think there is a bit more to it than that. IF you had a abstract base class that defined a method with no implementation, and you defined that method in the sub class, is that still … Read more
What is polymorphism, what is it for, and how is it used? 28 s 28 If you think about the Greek roots of the term, it should become obvious. Poly = many: polygon = many-sided, polystyrene = many styrenes (a), polyglot = many languages, and so on. Morph = change or form: morphology = study … Read more
I’m a bit confused about how Java generics handle inheritance / polymorphism. Assume the following hierarchy – Animal (Parent) Dog – Cat (Children) So suppose I have a method doSomething(List<Animal> animals). By all the rules of inheritance and polymorphism, I would assume that a List<Dog> is a List<Animal> and a List<Cat> is a List<Animal> – … Read more
I’m learning C++ and I’m just getting into virtual functions. From what I’ve read (in the book and online), virtual functions are functions in the base class that you can override in derived classes. But earlier in the book, when learning about basic inheritance, I was able to override base functions in derived classes without … Read more
I have a solid understanding of most OOP theory but the one thing that confuses me a lot is virtual destructors. I thought that the destructor always gets called no matter what and for every object in the chain. When are you meant to make them virtual and why? 1 19 Virtual destructors are useful … Read more
The clearest way to express polymorphism is via an abstract base class (or interface) public abstract class Human{ … public abstract void goPee(); } This class is abstract because the goPee() method is not definable for Humans. It is only definable for the subclasses Male and Female. Also, Human is an abstract concept — You cannot create … Read more
