Quick Answer: Can An Abstract Class Have A Constructor C++?

How do you declare an abstract class in C++?

An abstract class is a class that is designed to be specifically used as a base class.

An abstract class contains at least one pure virtual function.

You declare a pure virtual function by using a pure specifier ( = 0 ) in the declaration of a virtual member function in the class declaration..

Can abstract class 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 constructor be static?

No, we cannot define a static constructor in Java, If we are trying to define a constructor with the static keyword a compile-time error will occur. In general, static means class level. … We need to assign initial values for an instance variable we can use a constructor.

Can we declare constructor as private?

Yes, we can declare a constructor as private. If we declare a constructor as private we are not able to create an object of a class. We can use this private constructor in the Singleton Design Pattern.

How many default constructors can a class have?

one default constructorA class can only have one default constructor.

Can a constructor be final?

No, a constructor can’t be made final. A final method cannot be overridden by any subclasses. … But, in inheritance sub class inherits the members of a super class except constructors. In other words, constructors cannot be inherited in Java therefore, there is no need to write final before constructors.

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 a constructor have a return type C++?

Constructors don’t have return type. A constructor is automatically called when an object is created. If we do not specify a constructor, C++ compiler generates a default constructor for us (expects no parameters and has an empty body).

Why would you use an abstract class?

Abstract classes cannot be instantiated and are designed to be subclassed. They are used to provide some common functionality across a set of related classes while also allowing default method implementations. In this article, we’ll discuss a real world scenario for using an abstract class in Java.

Can we have static class?

The answer is YES, we can have static class in java. In java, we have static instance variables as well as static methods and also static block. Classes can also be made static in Java. In java, we can’t make Top-level (outer) class static.

What happens if a user forgets to define a constructor inside a class?

What happens if a user forgets to define a constructor inside a class? Explanation: The C++ compiler always provides a default constructor if one forgets to define a constructor inside a class.

Can constructor be static or final?

Automatically a constructor is called when an object of a class is created. It is syntactically similar to a method but it has the same name as its class and a constructor does not have a return type. One of the important property of java constructor is that it can not be final.

What is difference between abstract class and interface?

Abstract class can inherit another class using extends keyword and implement an interface. Interface can inherit only an inteface. Abstract class can be inherited using extends keyword. Interface can only be implemented using implements keyword.

Can we make abstract class as final?

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.

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 an 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.

Is an abstract class C++?

By definition, an abstract class in C++ is a class that has at least one pure virtual function (i.e., a function that has no definition). The classes inheriting the abstract class must provide a definition for the pure virtual function; otherwise, the subclass would become an abstract class itself.

Can an abstract class have a 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.