5 Principles of Object Oriented Design

Question 1

What are the 5 Principles of OOD

Answer 1

S - Single-responsiblity Principle
O - Open-closed Principle
L - Liskov Substitution Principle
I - Interface Segregation Principle
D - Dependency Inversion Principle

Question 2

Single-Responsibility Principle

Answer 2

A class should have one and only one reason to change, meaning that a class should have only one job.

Question 3

Liskov Substitution Principle

Answer 3

Let q(x) be a property provable about objects of x of type T. Then q(y) should be provable for objects y of type S where S is a subtype of T.

This means that every subclass or derived class should be substitutable for their base or parent class.

Question 4

Interface Segregation Principle

Answer 4

A client should never be forced to implement an interface that it doesn’t use, or clients shouldn’t be forced to depend on methods they do not use.

Question 5

Dependency Inversion Principle

Answer 5

Entities must depend on abstractions, not on concretions. It states that the high-level module must not depend on the low-level module, but they should depend on abstractions.

Question 6

Open-Closed Principle

Answer 6

Objects or entities should be open for extension but closed for modification.