Creating object with reference to Interface

Question

A reference variable can be declared as a class type or an interface type.If the variable is declared as an interface type, it can reference any object of any class that impleme

Answer 1

Interfaces are basically another way of - breaking the rules of single inheritance.

By using interfaces, a child class can, both inherit it's parents methods and be forced to implement it's interface methods. Resulting in an easy to extend and maintain inheritance tree etc.

The catch however is, when the child is referenced under the parent, you only have access to the parent methods. To access the interface methods, you will need to cast or create the child under the interface reference type.

Interfaces also allow the collection of multiple classes of different families to be collected under the interface type. To what benefit I am yet to discover.

In my opinion, it is pointless since I still cannot achieve fully blown polymorphism anyways - by just using the parent reference type and still have access to the interface implementations.