java实现单链表

早上清早起来，第一件事就是打开博客园随便的翻看下博客， 看到有篇文章提到的算法数据结构，实现一个单链表的操作。作者是使用c#编写的， 那么我这里通过java也来弄弄。

首先定义一个Node类

public class Node {
     protected Node next; //指针域  
     public  int data;//数据域  
       
     public Node( int data) {  
           this. data = data;  
     }  
       
     //显示此节点  
     public void display() {  
          System. out.print( data + " ");  
     }  
}

接下来定义一个单链表，并实现相关方法：

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;
    }
}

最后我们可以通过测试类来做相关测试:

public class TestLinkList {
    public static void main(String[] args) {  
        LinkList linkList = new LinkList();  
        linkList.addFirstNode(20);  
        linkList.addFirstNode(21);  
        linkList.addFirstNode(19);  
         //print19,21,20  
        linkList.add(1, 22); //print19,22,21,20  
        linkList.add(2, 23); //print19,22,23,21,20  
        linkList.add(3, 99); //print19,22,23,99,21,20  
      //调用此方法会print 19,22,23,99,21,20 
        linkList.displayAllNodes();  
        }
}

至此，对单链表的操作就笔记到这里了。