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Java · Interview Question

Why is it dangerous to base equals/hashCode on mutable fields in a polymorphic class hierarchy?

Detailed answer, explanation and code for this interview question. Ideal for Java interview preparation, coding rounds and viva questions.

Difficulty: MediumType: Subjective

Question Overview

Subject

Java

Asked in Companies

Problem Statement

Why is it dangerous to base equals/hashCode on mutable fields in a polymorphic class hierarchy?

Explanation

Mutations can break set/map invariants and lookup; cross-type symmetry/consistency can also be violated.

Practice Sets

This question appears in the following practice sets:

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Why is it dangerous to base equals/hashCode on mutable fields in a polymorphic class hierarchy? - Java | Preplance Interview Prep | Preplance

Master Interviews
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Why is it dangerous to base equals/hashCode on mutable fields in a polymorphic class hierarchy?

Problem Statement

Explanation

Practice Sets

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Master Interviews Anywhere, Anytime

Why is it dangerous to base equals/hashCode on mutable fields in a polymorphic class hierarchy?

Problem Statement

Explanation

Practice Sets

Related Questions

Why is Java considered platform independent?

Pick the correct mapping:

Which area holds per-thread call frames (locals, operand stack)?

Explain the delegation model of classloaders and why it matters for security.

What does the JIT do at runtime?

More from Java

Master Interviews
Anywhere, Anytime