OOP Demystified

1.  

What is abstraction?

2.  

When should abstraction be used in a program?

3.  

What is an abstract method?

4.  

Can an abstract method be called within a program?

5.  

What happens if an abstract method is not redefined?

6.  

Can an instance of an abstract class be declared in a program?

7.  

Can an abstract method be called directly by a subclass?

8.  

Must an abstract method be redefined by a subclass?

9.  

Must all methods in an abstract class be designated as abstract?

10.  

Must all methods in an abstract class be redefined in a subclass?

Answers

1.  

Abstraction is a way for the programmer of a super class to require the programmer of a subclass to define a method.

2.  

Abstraction should be used in a program when there isn t any way to define a good default method in the super class.

3.  

An abstract method is a method defined in a super class that must be redefined in a subclass that inherits the super class.

4.  

An abstract method cannot be called within a program.

5.  

A compiler error occurs if an abstract method is not redefined.

6.  

An instance of an abstract class cannot be declared in a program.

7.  

An abstract method cannot be called directly by a subclass.

8.  

A programmer of a subclass that inherits an abstract super class must redefine the abstract methods defined in the subclass, even if those methods are not called within the application.

9.  

A super class can contain a mixture of abstract methods and non-abstract methods.

10.  

Only abstract methods must be redefined in a subclass that inherits from the abstract super class.

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