How to sort CopyOnWriteArrayList

Question

I want to sort CopyOnWriteArrayList. But when I tried to run the following code

It is throwing unsorted operation exception.

Answer 1

In JDK1.8 can use sort(Comparator c) directly.

List list = new CopyOnWriteArrayList();

list.add(3);
list.add(4);
list.add(1);

list.sort(new Comparator() {
    @Override
    public int compare(Integer o1, Integer o2) {
        return o1 - o2;
    }
});