List 不安全

package pc;

import java.util.List;
import java.util.UUID;
import java.util.concurrent.CopyOnWriteArrayList;

public class D {
    public static void main(String[] args) {
//        List<String> list = new ArrayList<>(); //报错
//        List<String> list = new Vector<>(); //√速度慢
//        List<String> list = Collections.synchronizedList(new ArrayList<>());//√速度慢
        List<String> list = new CopyOnWriteArrayList<>();//√高效
        for (int i = 1; i <=10; i++) {
            new Thread(()->{
                list.add(UUID.randomUUID().toString().substring(0,5));
                System.out.println(list);
            },String.valueOf(i)).start();

        }
    }
}