SOLID Principles

Design Patterns & LLDTopic 1 of 105 questions

Q1Each SOLID principle with violations and fixes, the SRP–DIP clash, and SOLID over-engineering

SOLID is five rules: one job per class, extend without modifying, subtypes must substitute, small focused interfaces, and depend on abstractions not concretions.

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Q2Explain the five SOLID principles with a violation and fix for each

SOLID means one job per class, extend by adding not editing, subtypes must not break callers, keep interfaces small and role-based, and depend on abstractions you inject.

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Q3What is the Strategy pattern and how does it enforce the Open/Closed Principle

Strategy makes algorithms interchangeable behind one interface, chosen at runtime, so adding a new algorithm is a new class, never an edit to old code.

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Q4Why "don't over-engineer" is a core LLD skill, and answering "how would you extend this?" with the Open/Closed Principle

Build the simplest correct design and refactor when needed, then extend by adding a new class rather than modifying existing code, which is the Open/Closed Principle.

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Q5Which SOLID principles matter most in LLD?

In LLD, SRP keeps classes focused, OCP adds behaviour without edits, LSP guarantees substitutability, and DIP makes everything testable through injected abstractions.

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