Core Java · interview question
Given a class with mutable fields, what is a potential issue if instances are used as keys in a HashMap?
Multiple choiceHardchapter-4-curatedpremiumcore-javaequals-and-hashcode-in-collections
Answer and explanation
Correct answer
D. Keys may become irretrievable.
Why
If a key's fields are mutable and change after insertion, its hash code may change, making it irretrievable in the map. The key's identity is compromised, breaking contract rules.
Test yourself on Core Java
A free test with instant, explained results. No account needed.
More Core Java questions
- In a console shopping cart application, why might you separate input handling from calculations?
- What happens if a subclass does not implement an abstract method from its superclass?
- Why would you choose to use a switch statement instead of multiple if-else statements for handling order status?
- Which part of the following code is responsible for avoiding an off-by-one error?
- Why can using overly complex methods in an e-commerce application become a problem in production code?
- How can a class implementing an interface with a default method call that method from within an overridden method?