Java Interview Questions · interview question

Which practice avoids a common mistake with HashSet Membership and Deduplication?

Multiple choiceMediumjava-interview-2026interviewjavapitfall

Silence the HashSet Membership and Deduplication problem by using raw types, broad catches, or shared mutable state.Do not forget that HashSet correctness depends on consistent equals and hashCode behavior for custom element types.Prefer the version of HashSet Membership and Deduplication that makes behavior less predictable as long as the code compiles.Ignore the HashSet Membership and Deduplication issue and rely on team discipline instead of APIs or contracts.

Answer and explanation

Correct answer

B. Do not forget that HashSet correctness depends on consistent equals and hashCode behavior for custom element types.

Why

Do not forget that HashSet correctness depends on consistent equals and hashCode behavior for custom element types. This is a common failure mode in real Java code and a frequent interview follow-up.

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Which practice avoids a common mistake with HashSet Membership and Deduplication?

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