How can I resolve ConcurrentModificationException when modifying a List while iterating in Java 8 Streams?
I've looked through the documentation and I'm still confused about I'm encountering a `ConcurrentModificationException` when I attempt to modify a `List` while iterating over it using Java 8 Streams... I have a list of `String` elements that I want to filter out based on certain conditions, but I also need to remove some elements from the list during this process. Here's a simplified version of what I'm trying to achieve: ```java import java.util.ArrayList; import java.util.List; import java.util.stream.Collectors; public class Example { public static void main(String[] args) { List<String> items = new ArrayList<>(); items.add("apple"); items.add("banana"); items.add("cherry"); // Trying to remove items while filtering List<String> filteredItems = items.stream() .filter(item -> { if (item.equals("banana")) { items.remove(item); // This line is causing ConcurrentModificationException } return !item.equals("cherry"); }) .collect(Collectors.toList()); System.out.println(filteredItems); } } ``` When I run this code, I get the following error: ``` Exception in thread "main" java.util.ConcurrentModificationException at java.base/java.util.ArrayList$Itr.checkForComodification(ArrayList.java:1043) at java.base/java.util.ArrayList$Itr.next(ArrayList.java:990) at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195) at java.base/java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:413) at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:497) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:488) at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:550) at java.base/java.util.stream.AbstractPipeline.evaluateToArrayNode(AbstractPipeline.java:265) at java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:682) at java.base/java.util.stream.ReferencePipeline.toList(ReferencePipeline.java:574) at Example.main(Example.java:10) ``` I've tried using an explicit iterator to remove elements, but that seems cumbersome and goes against the functional programming style that I want to achieve using streams. What would be the best practice to safely remove elements from a list while performing stream operations in Java 8 without running into this exception? I recently upgraded to Java 3.9.