public static void main(String[] args) {
        ArrayList arrayList = new ArrayList();
        Node zhangsan = new Node("张三");
        Node lisi = new Node("李四");
        Node wanger = new Node("王二");

        //模拟双向链表，将表中元素依次连接起来
        zhangsan.next = lisi;
        lisi.next = wanger;
        wanger.pre = lisi;
        lisi.pre = zhangsan;

        //加入头指针和尾指针
        Node first = zhangsan;
        Node last = wanger;

        //将元素加入到arryList中
        arrayList.add(zhangsan);
        arrayList.add(lisi);
        arrayList.add(wanger);
        System.out.println(arrayList);

        //正向打印输出
        while (true){
            if(first==null){
                break;
            }
            System.out.println(first);
            first = first.next;
        }

        System.out.println("===========");
        //从尾指针打印输出
        while (true){
            if(last==null){
                break;
            }
            System.out.println(last);
            last = last.pre;
        }

        //添加元素麻子，添加在李四后面
        Node mazi = new Node("麻子");
        lisi.next = mazi;
        mazi.next = wanger;
        wanger.pre = mazi;
        mazi.pre = lisi;

        //此时first已经指向最后一个元素，因此需要重置first、
        first = zhangsan;
        //正向打印输出
        System.out.println("=======插入后的元素=======");
        while (true){
            if(first==null){
                break;
            }
            System.out.println(first);
            first = first.next;
        }
    }
}

class Node {
    public Object item;
    public Node next;
    public Node pre;

    public Node(Object name) {
        this.item = name;
    }

    @Override
    public String toString() {
        return "Node name=" + item;
    }
}