Which Iterator Is Fail Safe?

Iterator on ArrayList, HashMap classes are some examples of fail-fast Iterator. ... This is because, they operate on the clone of the collection, not on the original collection and that's why they are called fail-safe iterators. Iterator on CopyOnWriteArrayList, ConcurrentHashMap classes are examples of fail-safe Iterator.

Is iterator fail-safe in Java?

The iterator in Java is used to traverse over a collection's objects. The collections return two types of iterators, either it will be Fail Fast or Fail Safe. The Fail Fast iterators immediately throw ConcurrentModificationException in case of structural modification of the collection.

What is fail-safe and fail-fast in Java?

Fail-Safe. 1. Exception. Any changes in the collection, such as adding, removing and updating collection during a thread are iterating collection then Fail fast throw concurrent modification exception. The fail-safe collection doesn't throw exception.