28.集合1------List

    public static void main(String[] args) {
        List list = new ArrayList();
        list.add("1");
        list.add("2");
        list.add("3");
        ListIterator listIterator = list.listIterator();
        while (listIterator.hasNext()) {
            System.out.println(listIterator.next());
        }
        System.out.println("------------");

        while (listIterator.hasPrevious()) {
            System.out.println(listIterator.previous());
        }
        System.out.println("------------");
        listIterator.add("4");
        System.out.println(list);
    }

控制台输出:
1
2
3
------------
3
2
1
------------
[4, 1, 2, 3]