When should I use abstract classes and when should I use interfaces?

Question

When should I use abstract classes and when should I use interfaces? with considering latest version of C#.NET

Rajanikant Hawaldar · Answer

Use Interfaces when… 1)You see that something in your design will change frequently. 2)If various implementations only share method signatures then it is better to use Interfaces. 3)You need some classes to use some methods which you don't want to be included in the class, then you go for the interface, which makes it easy to just implement and make use of the methods defined in the interface. Use Abstract Class when… 1)If various implementations are of the same kind and use common behavior or status then abstract class is better to use. 2)When you want to provide a generalized form of abstraction and leave the implementation task with the inheriting subclass. 3)Abstract classes are an excellent way to create planned inheritance hierarchies. They're also a good choice for non leaf classes in class hierarchies. https://www.c-sharpcorner.com/article/when-to-use-abstract-class-and-interface-in-real-time-projects/

Alkesh Bijarniya · Answer

https://www.c-sharpcorner.com/article/when-to-use-abstract-class-and-interface-in-real-time-projects/

Vishal Yelve · Answer

Hi Anand, Please refer to ShivPrasad Koirala Sir's video, He has explained in depth. https://youtu.be/0EnSPBVrbG0 https://youtu.be/DMEyAYQ6Gks

Jignesh Kumar · Answer

Hi Anand SA, Please refer this link which will help you, https://www.c-sharpcorner.com/article/when-to-use-abstract-class-and-interface-in-real-time-projects/

Patel · Answer

https://softwareengineering.stackexchange.com/questions/400006/when-should-i-use-an-abstract-class-vs-an-interface

Satish Rathore · Answer

1) when you know scope of requirement use interface and when scope may change or extend use abstract class, 2) when you want all method to be public and force client to implement use interface and when you want different access modifier and do not force to implement on inheritance 3) when you use interface then you simply cannot change it in the end. Abstract classes always have extended compatibility and can still add the behavior without breaking the existing code.

Rajeev Kumar · Answer

Hi Anand Abstract classes should be used primarily for objects that are closely related, whereas interfaces are best suited for providing common functionality to unrelated classes . If you are designing small, concise bits of functionality, use interfaces. If you are designing large functional units, use an abstract class.