Cognitive Technology Team

Jun 23, 2024 · Fundamentals

Understanding Fail-Fast Iterators and ConcurrentModificationException in Java Collections

The article explains why fail‑fast iterators throw ConcurrentModificationException when a collection is modified during iteration, outlines two common scenarios that trigger the exception, and presents both incorrect and correct Java code examples along with strategies such as avoiding modifications, using synchronization, iterator.remove(), or switching to fail‑safe concurrent collections.