JAVA 实现单链表

 1 public class LinkNode {
 2     public String data;
 3     public LinkNode next;
 4     
 5     LinkNode(){
 6         this.data = "a";
 7         this.next = null;
 8     }
 9     
10     LinkNode(String string){
11         this.data = string;
12         this.next = null;
13     }
14 }

  1 public class LinkList {
  2 
  3     public LinkNode head = null;//头指针
  4     private LinkNode currentNode = null;//遍历用节点
  5     
  6     LinkList(){}
  7     LinkList(int n){
  8         for(int i = 0; i<n; i++){
  9             add();
 10         }
 11     }
 12     
 13     public int getLength(){
 14         if(head == null){
 15             return 0;
 16         }
 17         else{
 18             currentNode = head;
 19             int count = 0;
 20             while(currentNode != null){
 21                 currentNode  = currentNode.next;
 22                 count++;
 23             }
 24             return count;
 25         }
 26     }
 27     
 28     //头插法添加节点
 29     public void add(){
 30         LinkNode tempNode = new LinkNode();
 31         tempNode.next = head;
 32         head= tempNode;
 33     }
 34     
 35     //在第i个节点之后插入新节点
 36     public void insert(int i,String string){
 37         if(getLength() >= i){
 38             LinkNode tempNode = new LinkNode(string);
 39             if(i == 0){                                        //头指针后插入节点
 40                 tempNode.next = head;
 41                 head = tempNode;
 42             }
 43             else{
 44                 currentNode = head;
 45                 if(i == 1){                                    //第一个节点后插入
 46                     tempNode.next = currentNode.next;
 47                     currentNode.next = tempNode;
 48                 }
 49                 else{                                        //一般位置插入
 50                     for(int j =0; j < (i-1); j++){
 51                         currentNode = currentNode.next;
 52                     }
 53                     tempNode.next = currentNode.next;
 54                     currentNode.next = tempNode;
 55                 }
 56             }
 57         }
 58         else{
 59             System.out.println("要插入的位置不存在");
 60         }
 61     }
 62     
 63     //删除第i个节点
 64     public void delete(int i){
 65         if((getLength()>=i) && (i>0)){
 66             currentNode = head;
 67             if(i == 1){
 68                 head = currentNode.next;
 69             }
 70             else{
 71                 for(int j = 1; j<(i-1); j++){
 72                     currentNode = currentNode.next;
 73                 }
 74                 LinkNode tempNode = currentNode.next;
 75                 currentNode.next = tempNode.next;
 76             }
 77         }
 78         else{
 79             System.out.println("这个节点不存在");
 80         }
 81     }
 82     
 83     //修改第i个节点
 84     public void modify(int i,String string){
 85         if(getLength()>=i && (i>0)){
 86             currentNode = head;
 87             for(int j = 1; j<i; j++){
 88                 currentNode = currentNode.next;
 89             }
 90             currentNode.data = string;
 91         }
 92         else{
 93             System.out.println("这个节点不存在");
 94         }
 95     }
 96     
 97     //查询第i个节点
 98     public String search(int i){
 99         if(getLength()>=i && (i>0)){
100             currentNode = head;
101             for(int j = 1; j<i; j++){
102                 currentNode = currentNode.next;
103             }
104             return currentNode.data;
105         }
106         else{
107             System.out.println("这个节点不存在");
108             return null;
109         }
110     }
111     
112     public void display(){
113         currentNode = head;
114         while(currentNode != null){
115             System.out.println(currentNode.data.toString());
116             currentNode = currentNode.next;
117         }
118     }
119     
120     public static void main(String args[]){
121         //测试代码
122         /*LinkList ll = new LinkList(4);
123         ll.insert(4, "n");
124         ll.display();
125         System.out.println(ll.getLength());
126         ll.delete(5);
127         ll.display();
128         ll.insert(4, "v");
129         System.out.println(ll.search(5));*/
130     }
131 }