When to use abstract class and interface class

Question

Hello Guys What is difference between abstract class and interface class and iam just not understanding when to use abstract class and interface class in Programming .Just give the best example of this classes that i can understand and i can use in my Code. Thanks & Regards Muniyan

Sam Hobbs · Answer

I think the MSDN documentation is useful for this. See Abstract Classes . The important thing I think is that abstract classes can have some methods that are implemented but an interface cannot.

Satyapriya Nayak · Answer

Hi Muniyan Abstract class A class that cannot be instantiated. An abstract class is a class that must be inherited and have the methods overridden. An abstract class is essentially a blueprint for a class without any implementation. An abstract class is a special kind of class that cannot be instantiated. It normally contains one or more abstract methods or abstract properties. It provides body to a class. Interface An interface has no implementation; it only has the signature or in other words just the definition of the methods without the body. It's an abstract class with public abstract methods all of which must be implemented in the inherited classes. In which Scenario you will go for Interface or Abstract Class? Interfaces like classes define a set of properties methods and events. But unlike classes interfaces do not provide implementation. They are implemented by classes and defined as separate entities from classes. Even though class inheritance allows your classes to inherit implementation from a base class it also forces you to make most of your design decisions when the class is first published. Abstract classes are useful when creating components because they allow you specify an invariant level of functionality in some methods but leave the implementation of other methods until a specific implementation of that class is needed. They also version well because if additional functionality is needed in derived classes it can be added to the base class without breaking code. Difference Abstract class vs Interface In the interface all methods must be abstract in the abstract class some methods can be concrete. In the interface no accessibility modifiers are allowed which is ok in abstract classes. Please also refer Our recommended articles Thanks