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

In Java, the main difference between an interface and an abstract class lies in their implementation and usage. An interface can only contain method signatures and constant declarations, while an abstract class can have both abstract and concrete methods.

The key focus of an interface is to define a contract that a class must adhere to, allowing for multiple inheritance in Java. On the other hand, an abstract class serves as a partial implementation that can be extended by subclasses.

When choosing between an interface and an abstract class, consider whether you need to define a common behavior for multiple disparate classes (interface) or provide a blueprint with some implemented functionality for subclasses to extend (abstract class).

Understanding the nuances of interfaces and abstract classes can help in designing flexible and maintainable Java applications.

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