What is the difference between an abstract class and an interface in Java?

Understanding the Difference Between Abstract Class and Interface in Java

In Java, the main difference between an abstract class and an interface lies in their implementation and usage.

Abstract Class:

An abstract class in Java is a class that cannot be instantiated on its own and can contain both abstract (unimplemented) methods as well as concrete (implemented) methods. It provides a common base for its subclasses to extend and implement specific behavior.

Interface:

An interface in Java is a blueprint of a class that defines a set of methods that a class must implement. Unlike abstract classes, interfaces can only have method signatures without any implementation. Classes can implement multiple interfaces, allowing for a way to achieve multiple inheritances in Java.

Key Differences:

• An abstract class can have both abstract and concrete methods, while an interface can only have method signatures.
• A Java class can only inherit from one abstract class, but it can implement multiple interfaces.
• Abstract classes are useful when sharing code among closely related classes, while interfaces are used to define common behavior across unrelated classes.

Both abstract classes and interfaces play essential roles in Java programming, providing flexibility and code reusability in different scenarios.