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SOLID Principles in Practice
SOLID principles aren't just theory — they're the vocabulary interviewers use to evaluate your OOP design. Learn each principle with concrete before/after code examples and how to spot violations.
30 min read 2 sections 1 interview questions
SOLIDSingle Responsibility PrincipleOpen Closed PrincipleLiskov SubstitutionInterface SegregationDependency InversionOOPClean CodeRefactoringDesign PrinciplesLow Level Design
Why SOLID Matters in LLD Interviews
LLD interviewers explicitly evaluate whether your design follows SOLID. Common probes:
- "How would you handle a new requirement?" → tests Open/Closed Principle
- "What happens if we add a new payment method?" → tests extensibility
- "What would break if we changed how users are stored?" → tests Single Responsibility
You don't need to recite definitions. You need to apply the principles naturally during your design — and name them when you do.