Can We Make A Class Both Final And Abstract At The Same Time?

Can abstract method have body?

Abstract methods are declaration only and it will not have implementation.

It will not have a method body.

A Java class containing an abstract class must be declared as abstract class.

An abstract method can only set a visibility modifier, one of public or protected..

Can a static method be abstract?

If you declare a method in a class abstract to use it, you must override this method in the subclass. But, overriding is not possible with static methods. Therefore, an abstract method cannot be static.

Can we override interface?

If a base class already implements an interface and a derived class needs to implement the same interface but needs to override certain methods, you must reimplement the interface and set only the interface methods which need overriding. Both implement the ViewerEditable interface. …

Can we declare final inside abstract class and interface both?

Both abstract class and interface are used for abstraction. … Final Variables: Variables declared in a Java interface are by default final. An abstract class may contain non-final variables. Type of variables: Abstract class can have final, non-final, static and non-static variables.

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 use static variable in abstract class?

A single copy of the static variable is created for all instances of the class. … It can be directly accessed in a static method. An abstract class in Java is a class that cannot be instantiated.

Can we have final method in interface?

14 Answers. A final method can’t be overridden. … All methods are instance methods. Since the only goal of an interface is to have classes implementing them, and since methods in interfaces can’t have any implementation, making them final would make no sense: they would have no implementation, and could not be overridden …

Which is better abstract class or interface?

The short answer: An abstract class allows you to create functionality that subclasses can implement or override. An interface only allows you to define functionality, not implement it. And whereas a class can extend only one abstract class, it can take advantage of multiple interfaces.

Can a method or a class be final and abstract at the same time?

No, you cannot make an abstract class or method final in Java because the abstract and final are the mutually exclusive concept.

Which method Cannot be overridden?

A method declared final cannot be overridden. A method declared static cannot be overridden but can be re-declared. If a method cannot be inherited, then it cannot be overridden. A subclass within the same package as the instance’s superclass can override any superclass method that is not declared private or final.

Can constructor be static?

A static constructor does not take access modifiers or have parameters. A class or struct can only have one static constructor. Static constructors cannot be inherited or overloaded. A static constructor cannot be called directly and is only meant to be called by the common language runtime (CLR).

Can we override static method?

Can we Override static methods in java? We can declare static methods with the same signature in the subclass, but it is not considered overriding as there won’t be any run-time polymorphism. Hence the answer is ‘No’.

Can we declare static method as final?

Reports methods declared final and static. When a static method is overriden in a subclass it can still be accessed via the superclass making the final declaration not very necessary. Declaring a static method final does prevent subclasses from defining a static method with the same signature.

Is it possible to instantiate the abstract class?

Abstract classes cannot be instantiated, but they can be subclassed. When an abstract class is subclassed, the subclass usually provides implementations for all of the abstract methods in its parent class. However, if it does not, then the subclass must also be declared abstract .

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 an abstract class have a constructor C++?

A class with one (or more) virtual pure functions is abstract, and it can’t be used to create a new object, so it doesn’t have a constructor.

Why does an abstract class have a constructor?

The main purpose of the constructor is to initialize the newly created object. In abstract class, we have an instance variable, abstract methods, and non-abstract methods. … The constructor inside the abstract class can only be called during constructor chaining i.e. when we create an instance of sub-classes.

Can we declare method as final?

We can declare a method as final, once you declare a method final it cannot be overridden. So, you cannot modify a final method from a sub class. The main intention of making a method final would be that the content of the method should not be changed by any outsider.

Can we declare the static variables and methods in an abstract class?

Yes, of course you can define the static method in abstract class. you can call that static method by using abstract class,or by using child class who extends the abstract class. Also you can able to call static method through child class instance/object.

Can a method be 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 abstract class have static and final methods?

Yes, it can. But the final method cannot be abstract itself (other non-final methods in the same class can be).