What is the difference between interfaces and abstract classes in programming?

What is the difference between interfaces and abstract classes in programming?

Interfaces and abstract classes are both used to define contracts for classes, but they have key differences. An interface can only declare methods and properties, while an abstract class can provide some implementation. Additionally, a class can implement multiple interfaces but can only inherit from one abstract class.

Can you give me an example of when to use an interface?

Sure! Use an interface when you want to define a contract for classes that can be implemented in different ways. For example, if you have different types of payment methods (like credit card, PayPal, etc.), you can create a Payment interface that each payment class implements.

What about abstract classes? When should I use them?

Abstract classes are useful when you have a base class that should provide some common functionality to derived classes. For instance, if you have a base class called 'Animal' with a method 'makeSound()', you can define 'makeSound()' in the abstract class and let subclasses like 'Dog' and 'Cat' provide their specific implementations.

Are there any performance differences between using interfaces and abstract classes?

Generally, the performance difference is negligible. The choice between using an interface or an abstract class should be based on design needs rather than performance. However, abstract classes can have some overhead due to their implementation.