双向链表快速入门（增删改）

  1 package LinckedList;
  2 ?
  3 public class DoubleLinkedListDemo {
  4     public static void main(String[] args) {
  5         DoubleLinkedList s2 = new DoubleLinkedList();
  6         DoubleNode d1 = new DoubleNode(1,"a");
  7         DoubleNode d2 = new DoubleNode(2,"b");
  8         DoubleNode d3 = new DoubleNode(3,"c");
  9 ?
 10         s2.addNode(d1);
 11         s2.addNode(d3);
 12         s2.addNode(d2);
 13 ?
 14         s2.list();
 15 ?
 16         System.out.println("修改");
 17         DoubleNode d4 = new DoubleNode(3,"d");
 18         s2.upadate(d4);
 19         s2.list();
 20 ?
 21         System.out.println("删除");
 22         s2.del(2);
 23         s2.list();
 24 ?
 25     }
 26 }
 27 class DoubleLinkedList{
 28     private DoubleNode head = new DoubleNode(0,"");
 29 ?
 30     // 获取头节点
 31     public DoubleNode getHead(){
 32         return head;
 33     }
 34 ?
 35     // 遍历双向链表
 36     public void list(){
 37         if (head.next == null){
 38             System.out.println("链表为空");
 39             return;
 40         }
 41         DoubleNode temp = head.next;
 42         while (true){
 43             if (temp == null){
 44                 break;
 45             }
 46             System.out.println(temp);
 47             temp = temp.next;
 48         }
 49     }
 50 ?
 51     // 添加数据
 52     public void addNode(DoubleNode node){
 53         DoubleNode temp = head;
 54         boolean flag = false;
 55         while (true){
 56             if (temp.next == null){
 57                 break;
 58             }
 59             if (temp.next.id == node.id){
 60                 flag = true;
 61                 break;
 62             }else if(temp.next.id > node.id){
 63                 break;
 64             }
 65             temp = temp.next;
 66         }
 67         if (flag){
 68             System.out.println("Has exsist");
 69             return;
 70         }else {
 71             node.next = temp.next;
 72             temp.next = node;
 73             node.pre = temp;
 74         }
 75 ?
 76     }
 77 ?
 78     // 修改 双向链表的修改和单向链表一样，只是节点类型改成DoubleNode
 79     public void upadate(DoubleNode node){
 80         DoubleNode temp = head.next;
 81         boolean flag = false; // 判断是否找到当前值
 82         while (true){
 83             if (temp == null){
 84                 break;
 85             }
 86             if (temp.id == node.id){
 87                 flag = true;
 88                 break;
 89             }
 90             temp = temp.next;
 91         }
 92         if (flag){
 93             temp.id = node.id;
 94             temp.name = node.name;
 95         }else {
 96             System.out.println("不存在");
 97         }
 98     }
 99 ?
100     // 删除节点
101     // 说明
102     // 1. 对于双向链表，我们可以直接找到要删除的点
103     // 2. 找到后自我删除就好
104     public void del(int id){
105         if (head.next == null){
106             System.out.println("NULL List");
107             return;
108         }
109         DoubleNode temp = head.next;
110         boolean flag = false;
111         while (true){
112             if (temp == null){
113                 break;
114             }
115             if (temp.id == id){
116                 flag = true;
117                 break;
118             }
119             temp = temp.next;
120         }
121         // 判断flag
122         if (flag){
123             temp.pre.next = temp.next;
124             // 如果是最后这个节点就不需要执行下面这段话
125             if (temp.next != null){
126                 temp.next.pre = temp.pre;
127             }
128         }else {
129             System.out.println("不存在");
130         }
131     }
132 }
133 class DoubleNode{
134     public int id;
135     public String name;
136     public DoubleNode pre;
137     public DoubleNode next;
138 ?
139     public DoubleNode(int id, String name) {
140         this.id = id;
141         this.name = name;
142     }
143 ?
144     @Override
145     public String toString() {
146         return "DoubleNode{" +
147                 "id=" + id +
148                 ", name=‘" + name + ‘\‘‘ +
149                 ‘}‘;
150     }
151 }
152 ?