What is abstract class and its purpose?

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The purpose of an abstract class is to define some common behavior that can be inherited by multiple subclasses, without implementing the entire class. In C#, the abstract keyword designates both an abstract class and a pure virtual method.

Why can’t you instantiate an abstract class?

Because an abstract class is an incomplete class (incomplete in the sense it contains abstract methods without body and output) we cannot create an instance or object; the same way you say for an interface. You CAN instantiate an abstract class. You only need to provide a concrete subclass.

Can we have a final abstract method?

Yes, there may be “final” methods in “abstract” class. But, any “abstract” method in the class can’t be declared final. It will give “illegal combination of modifiers: abstract and final” error.

What is the difference between the final method and abstract method?

Difference between abstract method and final method in Java. The abstract method is incomplete while the final method is regarded as complete. The only way to use an abstract method is by overriding it, but you cannot override a final method in Java.

Can we override final method of abstract class?

In short, an abstract class cannot be final in Java, using both abstract and final modifier with a class is illegal in Java. An abstract method must be overridden to be useful and called but when you make the abstract method final it cannot be overridden in Java, hence there would be no way to use that method.