Can A Final Class Be Abstract?

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 abstract class have constructor?

Yes! Abstract classes can have constructors! Yes, when we define a class to be an Abstract Class it cannot be instantiated but that does not mean an Abstract class cannot have a constructor. Each abstract class must have a concrete subclass which will implement the abstract methods of that abstract class.

Can we declare constructor inside an interface?

No, you cannot have a constructor within an interface in Java. You can have only public, static, final variables and, public, abstract, methods as of Java7. From Java8 onwards interfaces allow default methods and static methods.

Can we declare constructor as final?

No, a constructor can’t be made final. A final method cannot be overridden by any subclasses. As mentioned previously, the final modifier prevents a method from being modified in a subclass.

Is it possible to have an abstract method in a final class?

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.

Can a class be final?

You can declare some or all of a class’s methods final. You use the final keyword in a method declaration to indicate that the method cannot be overridden by subclasses. … Note that you can also declare an entire class final. A class that is declared final cannot be subclassed.

Can a final class be inherited?

The final modifier for finalizing the implementations of classes, methods, and variables. The main purpose of using a class being declared as final is to prevent the class from being subclassed. If a class is marked as final then no class can inherit any feature from the final class. You cannot extend a final class.

Can we have a method which is both abstract and final?

A method can never, ever, ever be marked as both abstract and final, or both abstract and private. Think about it—abstract methods must be implemented (which essentially means overridden by a subclass) whereas final and private methods cannot ever be overridden by a subclass.

Can an interface be final?

If you make an interface final, you cannot implement its methods which defies the very purpose of the interfaces. Therefore, you cannot make an interface final in Java. Still if you try to do so, a compile time exception is generated saying “illegal combination of modifiers − interface and final”.

Can abstract class have static and final variables?

An abstract class may contain non-final variables. Type of variables: Abstract class can have final, non-final, static and non-static variables. Interface has only static and final variables. … A Java abstract class can have class members like private, protected, etc.

Can an abstract class be static?

Yes, abstract class can have Static Methods. The reason for this is Static methods do not work on the instance of the class, they are directly associated with the class itself.

Why Interface members are static and final?

Interface variables are static because java interfaces cannot be instantiated on their own. The value of the variable must be assigned in a static context in which no instance exists. The final modifier ensures the value assigned to the interface variable is a true constant that cannot be re-assigned.