Interfaces vs Abstract Classes in Java

nterfaces and abstract classes are two ways to define abstractions in object-oriented programming languages such as Java and C#. An interface is a group of related methods with empty bodies, while an abstract class is a class that may have both abstract methods (methods with empty bodies) and concrete methods (methods with bodies).

Here is an example in Java:

// Interface example
public interface Animal {
  public void makeSound();
}

// Abstract class example
public abstract class Animal {
  public abstract void makeSound();
  public void eat() {
    // Concrete method
  }
}

There are a few key differences between interfaces and abstract classes:

1. Interfaces can only contain abstract methods, while abstract classes can contain both abstract and concrete methods.
2. A class can implement multiple interfaces, but can only extend one abstract class.
3. An interface has no implementation, while an abstract class may have some implementation.
4. Interfaces are useful for defining a common set of methods that must be implemented by any class that implements the interface. Abstract classes are useful for providing a base implementation that can be shared by multiple subclasses.

It's important to choose the right tool for the job. If you want to define a set of methods that must be implemented by any class that implements the interface, you should use an interface. If you want to provide a base implementation that can be shared by multiple subclasses, you should use an abstract class.