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

Difficulty:

Medium

Questions:

1

Time Limit:

2 minutes

Passing Score:

100%

Question

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

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

Hint

Look for the option that protects correctness instead of hiding the problem.

Answer and rationale

Correct answer: A. Do not forget that HashSet correctness depends on consistent equals and hashCode behavior for custom element types.

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.

Track: Java