Encountering ConcurrentModificationException When Using CopyOnWriteArrayList with Java Streams
I've been researching this but I'm getting frustrated with I'm stuck trying to Quick question that's been bugging me - Quick question that's been bugging me - I'm working on a multi-threaded Java application using Java 11, and I'm encountering a `ConcurrentModificationException` when processing a `CopyOnWriteArrayList` with Java Streams..... My intention is to filter out certain elements from the list based on a condition and then collect the results into a new list. Here’s a snippet of the code that demonstrates the problem: ```java import java.util.List; import java.util.concurrent.CopyOnWriteArrayList; import java.util.stream.Collectors; public class Main { public static void main(String[] args) { List<String> list = new CopyOnWriteArrayList<>(List.of("apple", "banana", "cherry", "date")); list.forEach(s -> { if (s.startsWith("b")) { list.remove(s); // This line throws ConcurrentModificationException } }); List<String> filteredList = list.stream() .filter(s -> !s.startsWith("b")) .collect(Collectors.toList()); System.out.println(filteredList); } } ``` I assumed that `CopyOnWriteArrayList` would handle concurrent modifications safely. However, I still receive the `ConcurrentModificationException` on the line where I'm trying to remove elements. I’ve tried replacing the `remove` operation with a simple flag checking, but that just leads to elements not being removed as expected. I'm looking for guidance on how to correctly filter and modify a `CopyOnWriteArrayList` concurrently without running into this exception. Should I be using a different approach or collection for this scenario? Any advice would be greatly appreciated! Thanks in advance! Has anyone else encountered this? I'm on Ubuntu 20.04 using the latest version of Java. I'd love to hear your thoughts on this.