ConcurrentModificationException is best-effort and must never be logic

The fail-fast check is documented as a bug detector, not a guarantee. It can fire when nothing is wrong, and it can stay silent when something is. Code that catches it and retries is built on sand.

Full code & output

This topic is available to PRO members.

Sign in Create a free account

Run this yourself in the Online Java Compiler, spin up a live REST API in the API Sandbox, or practise with Java interview questions.

Published 2026-08-25