Abstract class and interfaces

Question

Hi, In real time in which scenarios, we use abstract class and interfaces

Vahaj uddin · Answer

We use abstract class in a situation when we want to give default functionality between classes which are related in inheritance hierarchy, and we use interface when we want to add some behaviour between classes which are not related in inheritance hierarchy abstract class Mammal | Cat, Dog, Graff, hippopotamus Since cat, dogs, graff, hippopotamus all are Mammal so will put all the default functionalities of them in mammal and they will inherit all these default functionalities from mammal. But there also a behaviour called Pet, both dog and cat can be pet but Graff and hippopotamus cant be, so will not put this functionality in abstract class and will make a seperate interface of it called Pettable which will be implement by both cat and dog but not by Graff and hippopotamus. We use Abstract class when we want to define the core identity of some class like Cat IS-A mammal, dog IS-A mammal, graff IS-A mammal so there is IS-A relationship between these classes, and we use interfaces when we want to add some extra behaviour in our classes which if we add in our abstract class then it can ruin core identity of our classes, as above if we add Pet behaviour in our abstract class then it ruin the core identity of Graff and hippopotamus.

Satyapriya Nayak · Answer

Hi Srinath, 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. Thanks

Vikrant Jadhav · Answer

Hi Srinath, Refer the below link will help you. http://www.codeproject.com/KB/cs/abstractsvsinterfaces.aspx Thanks & regards, Vikrant Jadhav Mark as a Correct Answer if this post is helpful to you.

Pankaj Rana · Answer

visit this link http://codeofdoom.com/wordpress/2009/02/12/learn-this-when-to-use-an-abstract-class-and-an-interface/

Abstract class and interfaces

Answers (4)