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Top 14 SOLID Principles Interview Questions and Answers

29/Sep/2020 | 15 minutes to read

QFLES is listing some Essential SOLID Principles Interview Questions and Answers for Freshers and mid level of Experienced Professionals prepared by Industry Experts. All answers for these SOLID Principles interview questions are given based on standard documents and tried to explain in simple and easiest way.

Best Answers to SOLID Principles Interview Questions

These questions are targeted for Object-Oriented Design Principles like SOLID Principles, DRY, SoC, KISS etc. C# Programming language is used to show examples.

1. What are the SOLID Principles?

SOLID Principles is an acronym of 5 principles in Object Oriented Design (OOD). Robert C. Martin introduced these 5 principles in his 2000 paper "Design Principles and Design Patterns".

  • S - Single Responsibility Principle
  • O - Open Close Principle
  • L - Liskov Substitution Principle
  • I - Interface Segregation Principle
  • D - Dependency Inversion Principle

1. Describe the Single Responsibility Principle (SRP).

In Object Oriented Programming, Single Responsibility (SRP) ensures that every module or class should be responsible for single functionality supported by software system. In other words, Every class should have one and only reason to change it.
For example, In ASP.NET MVC HomeController class should be responsible related to Home Page functionality of software system.

3. Describe the Open Close Principle (OCP).

Open Close Principle (OCP) states or ensures that A class, component or entity should be open for extension but close for modification. In detail, We can extend any class via Interface, Inheritance or Composition whenever it's required instead of opening a class and modifying it's code.
For example, suppose you have implemented a functionality to calculate area of Rectangle and after some time you need to calculate the area of Square, then In this case you should not modify your original class code to add extra code for square. Instead you should create one base class initially and now you should extend this base class by your square class.

4. Explain Liskov Substitution Principle (LSP).

Liskov Substitution Principle (LSP) states that Objects in a program can be replaced by the instances of their subtypes without modifying the correctness of a program.
In other words, if A is subtype of B then instances of B may be replaced by the instances of A without altering the program correctness.

5. Explain Interface Segregation Principle (ISP).

Interface Segregation Principle (ISP) states that use many client specific interfaces instead of one general purpose interface.
In other words No client should be forced to implement other methods which it does not require. It means it's better to create a separate interface and allow your classes to implement multiple interfaces.

6. Explain the Dependency Inversion Principle (DIP).

7. What is Inversion of Control (IoC)?

8. What is 'Don't repeat yourself (DRY)' Principle?

9. Explain the Separation of Concerns (SoC) design principle.

10. Explain KISS design principle.

11. How Encapsulation works as a design Principle?

12. What is YAGNI Principle?

Some General Interview Questions for SOLID Principles

1. How much will you rate your self in SOLID Principles?

When you attend an interview, Interviewer may ask you to rate your self in specific Technology like SOLID Principles, So It's depend on your knowledge and work experience in SOLID Principles.

2. What challenges did you face while working on SOLID Principles?

This question may be specific to your technology and completely depends on your past work experience. So you need to just explain the challenges you faced related to SOLID Principles in your Project.

3. What was your role in last Project related to SOLID Principles?

It's based on your role and responsibilities assigned to you and what functionality you implemented using SOLID Principles in your project. This question is generally asked in every interview.

4. How much experience do you have in SOLID Principles?

Here you can tell about your overall work experience on SOLID Principles.


We have covered some frequently asked SOLID Principles Interview Questions and Answers to help you for your Interview. All these Essential SOLID Principles Interview Questions are targeted for mid level of experienced Professionals and freshers.
While attending any SOLID Principles Interview if you face any difficulty to answer any question please write to us at Our IT Expert team will find the best answer and will update on portal. In case if we find any new SOLID Principles questions, we will update the same here.

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