Fail Fast vs Fail Safe Iterators in Java: A Comprehensive Guide

source : javapapers.com

Introduction:

Iterators play a crucial role in Java programming when it comes to traversing through collections. Among the various types of iterators, “Fail-Fast” and “Fail-Safe” are two distinct approaches. In this article, we will delve into the concepts of Fail-Fast and Fail-Safe iterators in Java, exploring their definitions, use cases, and providing practical code examples. Additionally, we will discuss scenarios where each type of iterator is most suitable, helping developers make informed decisions in their coding practices.

Fail-Fast Iterator:

A Fail-Fast iterator is designed to throw a ConcurrentModificationException if the collection is modified while the iterator is traversing it. This approach ensures that the iterator immediately becomes aware of any structural modification to the underlying collection.

Code Example — Fail-Fast Iterator:

List<String> failFastList = new ArrayList<>(Arrays.asList("Java", "Spring", "React"));

Iterator<String> iterator = failFastList.iterator();
while (iterator.hasNext()) {
    String element = iterator.next();
    failFastList.add("NewElement"); // ConcurrentModificationException thrown here
}