java单链表基本操作的实现 [问题描述] 1、用顺序表方式实现在线通讯录的设计，可以对通讯录作插入、删除、显示、查找、修改等操作。（必做题） 2、用单链表方式实现在线通讯录的设计，可以对通讯录作插入、删除、显示、查找、修改等操作。（必做题）

单链表基本操作的实现：

1. 定义节点类

class Node{
    String name; //姓名
    String phone; //电话
    Node next; //指向下一个节点的指针

    public Node(String name, String phone){
        this.name = name;
        this.phone = phone;
        this.next = null;
    }
}

2. 定义单链表类

class LinkedList{
    Node head; //头节点

    public LinkedList(){
        head = null;
    }

    //插入节点
    public void insert(String name, String phone){
        Node newNode = new Node(name, phone);
        if(head == null){
            head = newNode;
        }else{
            newNode.next = head;
            head = newNode;
        }
    }

    //删除节点
    public void delete(String name){
        if(head == null){
            System.out.println("链表为空！");
            return;
        }
        if(head.name.equals(name)){
            head = head.next;
            return;
        }
        Node prev = head;
        Node cur = head.next;
        while(cur != null){
            if(cur.name.equals(name)){
                prev.next = cur.next;
                return;
            }
            prev = cur;
            cur = cur.next;
        }
        System.out.println("未找到该节点！");
    }

    //查找节点
    public void find(String name){
        if(head == null){
            System.out.println("链表为空！");
            return;
        }
        Node cur = head;
        while(cur != null){
            if(cur.name.equals(name)){
                System.out.println("姓名：" + cur.name + "，电话：" + cur.phone);
                return;
            }
            cur = cur.next;
        }
        System.out.println("未找到该节点！");
    }

    //修改节点
    public void modify(String name, String phone){
        if(head == null){
            System.out.println("链表为空！");
            return;
        }
        Node cur = head;
        while(cur != null){
            if(cur.name.equals(name)){
                cur.phone = phone;
                System.out.println("修改成功！");
                return;
            }
            cur = cur.next;
        }
        System.out.println("未找到该节点！");
    }

    //显示链表
    public void display(){
        if(head == null){
            System.out.println("链表为空！");
            return;
        }
        Node cur = head;
        while(cur != null){
            System.out.println("姓名：" + cur.name + "，电话：" + cur.phone);
            cur = cur.next;
        }
    }
}

3. 测试

public static void main(String[] args) {
    LinkedList list = new LinkedList();
    list.insert("Tom", "123456");
    list.insert("Jerry", "234567");
    list.insert("John", "345678");
    list.display();
    list.delete("Jerry");
    list.display();
    list.find("Tom");
    list.modify("Tom", "111111");
    list.display();
}