What's the difference between abstraction and encapsulation?

Question

In interviews I have been asked to explain the difference between abstraction and encapsulation. My answer has been along the lines of

• Abstraction<

Answer 1

Encapsulation : Suppose I have some confidential documents, now I hide these documents inside a locker so no one can gain access to them, this is encapsulation.

Abstraction : A huge incident took place which was summarised in the newspaper. Now the newspaper only listed the more important details of the actual incident, this is abstraction. Further the headline of the incident highlights on even more specific details in a single line, hence providing higher level of abstraction on the incident. Also highlights of a football/cricket match can be considered as abstraction of the entire match.

Hence encapsulation is hiding of data to protect its integrity and abstraction is highlighting more important details.

In programming terms we can see that a variable may be enclosed is the scope of a class as private hence preventing it from being accessed directly from outside, this is encapsulation. Whereas a a function may be written in a class to swap two numbers. Now the numbers may be swapped in either by either using a temporary variable or through bit manipulation or using arithmetic operation, but the goal of the user is to receive the numbers swapped irrespective of the method used for swapping, this is abstraction.