Additional Notes
How would you explain the tradeoff of using a mutable object as a HashMap key in an interview?
Track: Java
Topic: Core Java
Focus: equals and hashCode in Collections
Java: equals and hashCode in Collections
Answer
Mutable keys can lead to unexpected lookup failures.
If a key's fields change after insertion, its hashCode may change, leading to incorrect bucket placement and lookup failures. For example, if a Product ID used as a key in a HashMap changes, retrieving the product using the old ID will fail.
If a key's fields change after insertion, its hashCode may change, leading to incorrect bucket placement and lookup failures. For example, if a Product ID used as a key in a HashMap changes, retrieving the product using the old ID will fail.
Topics: Core Java equals and hashCode in Collections Java