Core Java · interview question
How might using a mutable object as a key in a HashMap lead to subtle bugs?
Multiple choiceHardchapter-4-curatedpremiumcore-javaequals-and-hashcode-in-collections
Answer and explanation
Correct answer
C. The mutable key can be changed, making it irretrievable.
Why
When a mutable key's state changes, its hashCode may change, making the key irretrievable. This breaks the contract that the key's hashCode and equals relationship should remain consistent during its lifetime.
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