How to avoid “ConcurrentModificationException” while removing elements from `ArrayList` while iterating it? [duplicate]

Answer 1

While other suggested solutions work, If you really want the solution to be made thread safe you should replace ArrayList with CopyOnWriteArrayList

    //List s = new ArrayList<>(); //Will throw exception
    List s = new CopyOnWriteArrayList<>();
    s.add("B");
    Iterator it = s.iterator();
    s.add("A");

    //Below removes only "B" from List
    while (it.hasNext()) {
        s.remove(it.next());
    }
    System.out.println(s);