实现双向链表

 1 class Node{
 2     int data;
 3     Node next;
 4     Node(int data){
 5         this.data=data;
 6     }
 7 }
 8 public class MyNodes {
 9     private Node head;
10     private Node last;
11     private int size;
12     public Node get(int index){
13         if(index<0 || index>=size){
14             return  null;
15         }
16         Node temp=head;
17         for (int i=0;i<index ; i++){
18             temp=temp.next;
19         }
20         return temp;
21     }
22     public void insert(int data,int index) throws Exception{
23         if(index<0 || index>size){
24             throw new IndexOutOfBoundsException("超出链表节点范围");
25         }
26         Node insertNode=new Node(data);
27         if(size==0){
28             head=insertNode;
29             last=insertNode;
30         }else if(index==0){
31             //头部插入
32             insertNode.next=head;
33             head=insertNode;
34         }else if(index==size){
35             //尾部插入
36             last.next=insertNode;
37             last=insertNode;
38         }else{
39             //中间插入
40             Node prevNode=get(index-1);
41             Node nextNode=get(index);
42             prevNode.next=insertNode;
43             insertNode.next=nextNode;
44         }
45         size++;
46     }
47     public void remove(int index)throws Exception{
48         if(index<0 || index>size)throw new Exception("超出范围");
49         if(index==0){
50             //删除首元素
51             head=head.next;
52         }else if(index==size-1){
53             Node temp =get(index-1);
54             last=temp;
55             last.next=null;
56             temp.next=null;
57         }else{
58             //删除中间元素
59             Node Pre_temp=get(index-1);
60             Node Last_temp=get(index+1);
61             Pre_temp.next=Last_temp;
62         }
63         size--;
64     }
65     public void output(){
66         Node temp=head;
67         while (temp !=null){
68             System.out.println(temp.data);
69             temp=temp.next;
70         }
71     }
72 
73 }