JAva遍歴しながら削除する問題

    /**
     *        （      users.remove()     List   ConcurrentModificationException）
     */
    public static void list(){
        List users = getUsers();
        Iterator iterator = users.iterator();
        while (iterator.hasNext()){
        //      
            if (iterator.next().getId()>0 && iterator.next().getId()<3){
                iterator.remove();
            }
        }
        for (User user:users){
            System.out.println(user.getName());
        }
    }
    /**
     *      
     */
    public static void set(){
        Set users = getSetUsers();
        Iterator iterator = users.iterator();
        while (iterator.hasNext()){
            //      
            if (iterator.next().getId()>0 && iterator.next().getId()<3){
                iterator.remove();
            }
        }
        for (User user:users){
            System.out.println(user.getName());
        }
    }