Why am I getting java.util.ConcurrentModificationException?

Question

As I run the following code :

    import java.util.LinkedList;

    class Tester {
      public static void main(String args[]) {
        LinkedList

        

Answer 1

The ConcurrentModificationException is thrown when iterating through the list and at the same time when you are trying to modify (add/remove) the contents of the list either through another thread or in a loop.

You can try using ConcurrentLinkedQueue or as John stated do a copy and modify the original in iteration.

Queue list = new ConcurrentLinkedQueue();

list.add("suhail");
list.add("gupta");
list.add("ghazal");
list.add("poetry");
list.add("music");
list.add("art");

int size = list.size();

for(int i = 0; i < size; i++){
    list.add("art");
    list.remove("art");
    System.out.println(list);
}