Can an abstract class implement an interface?

Inhaltsverzeichnis:

1. Can an abstract class implement an interface?
2. Is abstract class static?
3. Why can't an abstract method be static?
4. CAN interface have a constructor?
5. Can abstract class have private constructor?
6. Can a class have virtual destructor?
7. Can a pure virtual class have a constructor?
8. Can we have pure virtual destructor?
9. Do I need a virtual destructor?
10. What is pure virtual function?
11. Can pure virtual function have body C++?
12. What is virtual base class with example?
13. Is a pure virtual function C++?
14. Can abstract method have body?
15. How do we declare an abstract class?
16. Can an abstract class be instantiated?

Can an abstract class implement an interface?

Java Abstract class can implement interfaces without even providing the implementation of interface methods. Java Abstract class is used to provide common method implementation to all the subclasses or to provide default implementation.

Is abstract class 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 can't an abstract method be static?

An abstract class cannot have a static method because abstraction is done to achieve DYNAMIC BINDING while static methods are statically binded to their functionality. A static method means behavior not dependent on an instance variable, so no instance/object is required. Just the class.

CAN interface have a constructor?

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.

Can abstract class have private constructor?

If you create an abstract class with only private constructors, the class is practically useless as no instances can ever be created. If the intention is to create a utility class with only static methods (like the Math class in the java.

Can a class have virtual destructor?

Destructors in the Base class can be Virtual. Whenever Upcasting is done, Destructors of the Base class must be made virtual for proper destrucstion of the object when the program exits. NOTE: Constructors are never Virtual, only Destructors can be Virtual.

Can a pure virtual class have a constructor?

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.

Can we have pure virtual destructor?

Yes, it is possible to have pure virtual destructor. Pure virtual destructors are legal in standard C++ and one of the most important things to remember is that if a class contains a pure virtual destructor, it must provide a function body for the pure virtual destructor.

Do I need a virtual destructor?

Virtual keyword for destructor is necessary when you want different destructors should follow proper order while objects is being deleted through base class pointer. ... If your base class destructor is NOT virtual then only base class object will get deleted(because pointer is of base class "Base *myObj").

What is pure virtual function?

A pure virtual function or pure virtual method is a virtual function that is required to be implemented by a derived class if the derived class is not abstract. Classes containing pure virtual methods are termed "abstract" and they cannot be instantiated directly.

Can pure virtual function have body C++?

Yes, a pure virtual function can have a body. All pure virtual means is that you can't call the function using an object that has declared or has inherited the pure virtual function. Because of this, you cannot create objects of classes with pure virtual functions.

What is virtual base class with example?

Virtual base classes are used in virtual inheritance in a way of preventing multiple “instances” of a given class appearing in an inheritance hierarchy when using multiple inheritances.

Is a pure virtual function C++?

A pure virtual function is a virtual function in C++ for which we need not to write any function definition and only we have to declare it. It is declared by assigning 0 in the declaration. ... If an Abstract Class has derived class, they must implement all pure virtual functions, or else they will become Abstract too.

Can abstract method have body?

A concrete class is a subclass of an abstract class, which implements all its abstract method. Abstract methods cannot have body. Abstract class can have static fields and static method, like other classes. An abstract class cannot be declared as final.

How do we declare an abstract class?

You create an abstract class by declaring at least one pure virtual member function. That's a virtual function declared by using the pure specifier ( = 0 ) syntax. Classes derived from the abstract class must implement the pure virtual function or they, too, are abstract classes.

Can an abstract class be instantiated?

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 .