Question

Select all correct options in the list below about concrete and abstract classes Select one or more: a. Concrete classes can be instantiated b. Abstract classes must contain at least one abstract method c. Only concrete classes can be super classes d. Abstract classes (using the "abc" library) can be instantiated e. Concrete classes often contain abstract methods f. Both concrete and abstract classes can be super classes that other classes inherit from g. Only abstract classes can be super classes

Answer 1

Explanations:

Concrete Class:

A concrete class is a clas that has an implementation for all the methods contained in it and can not essentially have any unimplemented method. It can extend an abstract class or implement an interface as long as it implements all their methods. It is, thus, a complete class and can be instantiated.

Abstract Class:

An abstract class is a class that is declared abstract and it may or may not include abstract methods.They can not be instantiated but can be subclassed.

Precisely, any class that is not abstract is a concrete class.

In the light of the above discussions, each of the first 4 subparts are reviewed as follows:

a. Concrete classes can be instantiated.,,TRUE

b. Abstract claases must contain atleast one abstract method...FALSE ( may or may not contain abstract method)

c. Only concrete classes can be superclasses...FALSE ( abstract classes can be subclassed as well)

d. Abstract classes ( using the "abc" library) can be instantiated...FALSE ( they can not be instantiated)

This answers the first 4 subparts of the question and the other subparts can also be answered similarly based on the explanation as provided above.