CopyOnWriteArrayList was introduced in Java 5 version. It is a

thread-safe collection. It is similar to an ArrayList.

In CopyOnWriteArrayList, all mutative operations (add, set etc.)

are implemented by making a fresh copy of the underlying array.

Iterator of CopyOnWriteArrayList is guaranteed to not throw

ConcurrentModificationException. But Iterator also does not reflect

any additions, removals that happened to list after the Iterator was

created.

All elements including null are permitted in CopyOnWriteArrayList.

https://www.tutorialspoint.com/Difference-between-ArrayList-and-CopyOnWriteArrayList-in-Java#:~:text=CopyOnWriteArrayList%20is%20thread%20safe.&text=ArrayList%20iterator%20is%20fail%2Dfast,never%20throw%20ConcurrentModificationException%20during%20iteration.