Top 50 SOLID Principles Interview Questions & Answers (2026)

01 What are the SOLID principles? 02 What does the Single Responsibility Principle (SRP) mean? 03 What does the Open/Closed Principle (OCP) mean? 04 What does the Liskov Substitution Principle (LSP) mean? 05 What does the Interface Segregation Principle (ISP) mean? 06 What does the Dependency Inversion Principle (DIP) mean? 07 Why are SOLID principles important in software development? 08 What is a "code smell" and how does it relate to SOLID? 09 Give an example of SRP violation. 10 How does OCP promote extensibility? 11 What is the difference between SOLID principles and design patterns? 12 What is tight coupling and how does it relate to SOLID? 13 What is loose coupling and why is it desirable? 14 How does SRP help with testing? 15 What is cohesion in software design? 16 How does ISP differ from SRP? 17 What is dependency injection? 18 How does DIP relate to dependency injection? 19 What is the role of interfaces/abstractions in SOLID? 20 What is a "god class" and which SOLID principle does it violate?

01 How would you refactor a class that violates SRP? 02 How does the Strategy pattern support OCP? 03 What are the conditions for LSP compliance? 04 How does ISP prevent "fat interfaces"? 05 What is the difference between DIP and dependency injection containers? 06 How does SOLID relate to GRASP principles? 07 How do SOLID principles apply to functional programming? 08 What are the trade-offs of strictly following SOLID? 09 How does OCP work with inheritance vs composition? 10 What is the Barbara Liskov quotation that defines LSP? 11 How does DIP improve testability? 12 What is "design by contract" and how does it relate to LSP? 13 How do SOLID principles apply to microservices? 14 What is cohesion vs coupling and how do SOLID principles address both? 15 How do you apply SOLID in a legacy codebase? 16 How does the Decorator pattern support OCP? 17 What is "interface pollution" and which principle prevents it? 18 How do SOLID principles relate to YAGNI and DRY? 19 How does SRP apply at the module/package level? 20 What are common misconceptions about OCP?

01 How do SOLID principles apply to domain-driven design? 02 How do you balance SOLID principles with pragmatic software development? 03 How does the Hexagonal Architecture (Ports and Adapters) apply DIP? 04 What is the relationship between SOLID and Clean Architecture? 05 How does LSP interact with covariance and contravariance in type systems? 06 How do SOLID principles apply to event-driven architectures? 07 What metrics can you use to measure SOLID compliance? 08 How do SOLID principles evolve in a growing codebase? 09 How do SOLID principles differ in dynamically-typed vs statically-typed languages? 10 How do you teach SOLID principles to a development team?