DRY, KISS, YAGNI & Other Principles

Design Patterns & LLDTopic 2 of 104 questions

Q1The DRY ("Don't Repeat Yourself") principle, how to follow it, and applying it carefully in microservices

Every rule or piece of knowledge should live in exactly one place, so a change is a single safe edit – but only unify things that are truly the same knowledge.

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Q2KISS and YAGNI principles, balancing them against DRY, and real YAGNI violations

KISS says prefer the simplest thing that works, YAGNI says do not build it until you actually need it, and both guard against over-engineering.

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Q3Time complexity and space complexity, with common Big-O examples

Time complexity is how running time scales with input size, space complexity is how extra memory scales, and Big-O names the growth rate ignoring constants.

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Q4How to create an immutable class in Java (final class, private final fields, no setters, defensive copies)

Make the class final, all fields private final and set once, no setters, and defensively copy anything mutable coming in or going out.

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