package com.tyxh.link;

//节点类

public class Node {

     protected Node next; //指针域

     protected int data;//数据域

     public Node( int data) {

           this. data = data;

     }

     //显示此节点

     public void display() {

          System. out.print( data + " ");

     }

}

package com.tyxh.link;

//单链表

public class LinkList {

     public Node first; // 定义一个头结点

     private int pos = 0;// 节点的位置

     public LinkList() {

           this. first = null;

     }

     // 插入一个头节点

     public void addFirstNode( int data) {

          Node node = new Node(data);

          node. next = first;

           first = node;

     }

     // 删除一个头结点,并返回头结点

     public Node deleteFirstNode() {

          Node tempNode = first;

           first = tempNode. next;

           return tempNode;

     }

     // 在任意位置插入节点 在index的后面插入

     public void add(int index, int data) {

          Node node = new Node(data);

          Node current = first;

          Node previous = first;

           while ( pos != index) {

              previous = current;

              current = current. next;

               pos++;

          }

          node. next = current;

          previous. next = node;

           pos = 0;

     }

     // 删除任意位置的节点

     public Node deleteByPos( int index) {

          Node current = first;

          Node previous = first;

           while ( pos != index) {

               pos++;

              previous = current;

              current = current. next;

          }

           if(current == first) {

               first = first. next;

          } else {

               pos = 0;

              previous. next = current. next;

          }

           return current;

     }

     // 根据节点的data删除节点(仅仅删除第一个)

     public Node deleteByData( int data) {

          Node current = first;

          Node previous = first; //记住上一个节点

           while (current. data != data) {

               if (current. next == null) {

                    return null;

              }

              previous = current;

              current = current. next;

          }

           if(current == first) {

               first = first. next;

          } else {

              previous. next = current. next;

          }

           return current;

     }

     // 显示出所有的节点信息

     public void displayAllNodes() {

          Node current = first;

           while (current != null) {

              current.display();

              current = current. next;

          }

          System. out.println();

     }

     // 根据位置查找节点信息

     public Node findByPos( int index) {

          Node current = first;

           if ( pos != index) {

              current = current. next;

               pos++;

          }

           return current;

     }

     // 根据数据查找节点信息

     public Node findByData( int data) {

          Node current = first;

           while (current. data != data) {

               if (current. next == null)

                    return null;

              current = current. next;

          }

           return current;

     }

}

package com.tyxh.link;

//测试类

public class TestLinkList {

     public static void main(String[] args) {

          LinkList linkList = new LinkList();

          linkList.addFirstNode(20);

          linkList.addFirstNode(21);

          linkList.addFirstNode(19);

           //19,21,20

          linkList.add(1, 22); //19,22,21,20

          linkList.add(2, 23); //19,22,23,21,20

          linkList.add(3, 99); //19,22,23,99,21,20

          linkList.displayAllNodes();

//        Node node = linkList.deleteFirstNode();

//        System.out.println("node : " + node.data);

//        linkList.displayAllNodes();

//        node = linkList.deleteByPos(2);

//        System.out.println("node : " + node.data);

//        linkList.displayAllNodes();

//        linkList.deleteFirstNode();

          Node node = linkList.deleteByData(19);

//        Node node = linkList.deleteByPos(0);

          System. out.println( "node : " + node. data);

          linkList.displayAllNodes();

          Node node1 = linkList.findByPos(0);

          System. out.println( "node1: " + node1. data);

          Node node2 = linkList.findByData(22);

          System. out.println( "node2: " + node2. data);

     }

}