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Java: Which practice avoids a common mistake with HashMap Internals?

Difficulty:

Medium

Questions:

1

Time Limit:

2 minutes

Passing Score:

100%

Question

Which practice avoids a common mistake with HashMap Internals?

  1. Ignore the HashMap Internals issue and rely on team discipline instead of APIs or contracts.
  2. Do not use mutable key fields that can change the hash-relevant state after insertion.
  3. Silence the HashMap Internals problem by using raw types, broad catches, or shared mutable state.
  4. Prefer the version of HashMap Internals 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: B. Do not use mutable key fields that can change the hash-relevant state after insertion.

Do not use mutable key fields that can change the hash-relevant state after insertion. This is a common failure mode in real Java code and a frequent interview follow-up.

Track: Java