package com;

//接收客户端发送消息的线程类

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

class ChatReceive extends Thread{
    private Socket socket;
    public ChatReceive(Socket socket){
        this.socket = socket;
    }
    @Override
    public void run() {
        super.run();
    }

    //实现接收客户端发送的消息
    private void receiveMsg(){
        BufferedReader nb = null;
        try {
            nb = new BufferedReader(new InputStreamReader(this.socket.getInputStream()));
            while (true){
                String msg = nb.readLine();
                synchronized ("abc"){
                    //把读取到的数据写入公共数据区
                    CharRoomServer.buf="["+this.socket.getInetAddress()+"]"+msg;
                    //唤醒发送消息的线程对象
                    "abc".notifyAll();
                }
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            if (nb!=null){
                try {
                    nb.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (this.socket!=null){
                try {
                    this.socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

//xiang客户端发送消息的线程类

class ChatSend extends Thread{
    private Socket socket;
    public ChatSend(Socket socket){
        this.socket = socket;
    }
    @Override
    public void run() {
        sendMsg();
    }


    //将公共数据区的消息发送给客户端

    private void sendMsg(){
        PrintWriter pw = null;
        try {
            pw = new PrintWriter(this.socket.getOutputStream());
            while (true){
                synchronized ("abc"){
                    //让发送消息的线程处于等待状态
                    "abc".wait();
                    //将公共数据区的消息发送给客户端
                    pw.println(CharRoomServer.buf);
                    pw.flush();
                }
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            if (pw!=null){
                pw.close();
            }
            if (this.socket!=null){
                try {
                    this.socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

public class CharRoomServer {
    //定义公共数据区
    public static String buf;
    public static void main(String[] args)  {
        System.out.println("Chat Server Version 1.0");
        System.out.println("Listen at 8888");
        ServerSocket serverSocket = null;
        try {
            while (true){
                Socket socket = serverSocket.accept();
                System.out.println("连接到："+socket.getInetAddress());
                new ChatReceive(socket).start();
                new ChatSend(socket).start();
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            if (serverSocket!=null){
                try {
                    serverSocket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

"C:\Program Files\Java\jdk-15.0.1\bin\java.exe" -Didea.launcher.port=51224 "-Didea.launcher.bin.path=C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.2\bin" -Dfile.encoding=UTF-8 -classpath "C:\Users\Administrator\IdeaProjects\socketDemo\out\production\socketDemo;C:\Program Files\JetBrains\IntelliJ IDEA 2019.3.2\lib\idea_rt.jar" com.intellij.rt.execution.application.AppMainV2 com.CharRoomServer

Chat Server Version 1.0

Listen at 8888

java.lang.NullPointerException: Cannot invoke "java.net.ServerSocket.accept()" because "serverSocket" is null

at com.CharRoomServer.main(CharRoomServer.java:111)

at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)

at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.base/java.lang.reflect.Method.invoke(Method.java:564)

at com.intellij.rt.execution.application.AppMainV2.main(AppMainV2.java:131)

Process finished with exit code 0

找不到解决方法来

用equals方法判断相同后相同的是被删掉了，还是就没有添加进去

这一节，我百度了一下，就是说一个数据hash值是一定的，当hash值经过运算后，放入节点后再放入对应的数组中，接下来运算相同的就放入同一个位置用链表连接起来，是不是这样理解

想问一下有没有老师上课用的中文的api帮助文档

是我看的顺序有问题还是我前面没学好，我咋不记得学过File呢

对上一个问题我可不可以这样理解，就是在一张表中，我要找一个人，ArrayList集合就是我知道它的名字和学号，学号是有序的，而LinkedList是我只知道它的名字，所以找人的时候，用ArrayList就很快找到，而用LinkedList就更慢，但是这就说不通它的底层源码，LinkedList底层是用了二分法，那我找人的时候怎么确定它在前面还是后面，如果是根据索引那还是矛盾的啊

LinkedList说是查询慢是因为没有索引，但是这章中的add像特定位置加元素，就是找到它的索引，然后再加元素，这不就矛盾了吗

老师，这个假设修正法，我可以理解为开始假设是对的，接下来把所有错的列出来吗

这个copyOf方法返回的是新的数组还是就是在原来的数组上扩容

/**
 * 创建发送消息类
 */

class ClientSend extends Thread {
    private  Socket socket;
    public ClientSend(Socket socket){
        this.socket = socket;
    }
    @Override
    public void run() {
        this.sendMsg();

    }
    /**
     * 发送消息
     */
    private void sendMsg(){
        Scanner scanner = null;
        PrintWriter pw = null;
        try {
            //键盘输入
            scanner = new Scanner(System.in);
            //创建向对方输出消息的流对象
            pw = new PrintWriter(this.socket.getOutputStream());
            while (true){
                String msg = scanner.nextLine();
                if ("exit".equals(msg)){
                    break;
                }
                pw.println(msg);
                pw.flush();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (pw != null){
                pw.close();
            }
            if (scanner != null){
                scanner.close();
            }
            if(this.socket!=null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }
}

/**
 * 创建接收消息线程类
 */
class ClientReceive extends Thread {
    private Socket socket;
    public ClientReceive(Socket socket){
        this.socket = socket;
    }
    @Override
    public void run() {

    }
    /**
     * 接收消息的方法
     */
    private void receiveMsg(){
        BufferedReader br = null;
        try {
            br = new BufferedReader(new InputStreamReader(this.socket.getInputStream()));
            while (true){
                String msg = br.readLine();
                System.out.println("他说： " +msg );

            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (br!=null){
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

public class PointSocketClient {
    public static void main(String[] args)  {

        try {
            Socket socket = new Socket("127.0.0.1",8888);
            System.out.println("连接成功");
            new ClientSend(socket).start();
            new ClientReceive(socket).start();
        } catch (IOException e) {
            e.printStackTrace();
        }
        
    }
}

/**
 * 创建发送消息类
 */

class Send extends Thread{
    private  Socket socket;
    public Send(Socket socket){

        this.socket = socket;
    }
    @Override
    public void run() {
        this.sendMsg();

    }

    /**
     * 发送消息
     */
    private void sendMsg(){
        Scanner scanner = null;
        PrintWriter pw = null;
        try {
            //键盘输入
            scanner = new Scanner(System.in);
            //创建向对方输出消息的流对象
            pw = new PrintWriter(this.socket.getOutputStream());
            while (true){
                String msg = scanner.nextLine();
                if ("exit".equals(msg)){
                    break;
                }
                pw.println(msg);
                pw.flush();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (pw != null){
                pw.close();
            }
            if (scanner != null){
                scanner.close();
            }
            if(this.socket!=null){
                try {
                    socket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }
}
/**
 * 创建接收消息线程类
 */
class Receive extends Thread{
    private  Socket socket;

    public Receive(Socket socket){
        this.socket = socket;
    }

    @Override
    public void run() {
        this.receiveMsg();

    }
    /**
     * 接收消息的方法
     */
    private void receiveMsg(){
        BufferedReader br = null;
        try {
            br = new BufferedReader(new InputStreamReader(this.socket.getInputStream()));
            while (true){
                String msg = br.readLine();
                System.out.println("他说： " +msg );

            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if (br!=null){
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}
public class PointSocketServer {
    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        try {
            serverSocket =new ServerSocket(8888);
            System.out.println("服务器启动等待连接.....");
            Socket socket = serverSocket.accept();
            System.out.println("连接成功");
            new Send(socket).start();
            new Receive(socket).start();
        } catch (Exception e) {
            e.printStackTrace();
        }finally {
            if (serverSocket != null){
                try {
                    serverSocket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

老师我这个代码只有客户端给服务端发消息的收回会输出

服务端给客户端发消息时没有反应，麻烦老师看下

package com.baizhan.test;

public class MyDoubleLinkedList <E>implements MyList<E> {
    class Node<E>{
        E item;
        Node<E> prev; //记录前一个节点对象
        Node<E> next; //记录下一个节点对象

        public Node(E item, Node<E> prev, Node<E> next) {
            this.item = item;
            this.prev = prev;
            this.next = next;
        }
    }
    private Node head;
    private Node tail;
    private int size;
    @Override
    public void add(E element) {
        linkLast(element);
    }
  private void linkLast(E element){
        Node t=this.tail;  //获取尾节点
        Node<E> node=new Node<>(element,t,null);   //创建节点
      //将新节点定义为尾节点
        this.tail=node;
        if(t==null){
            this.head=node;
        }else{
            t.next=node;
        }
        size++;
  }
    @Override
    public E get(int index) {
        chickIndex(index);
        Node<E> node =getNode(index);
        return node.item;
    }
private void chickIndex(int index){
    if (!(index>0 && index<size)) {
        throw new IndexOutOfBoundsException("Index:"+index+"size:"+size);
    }
}
private Node getNode(int index){
        if(index<(this.size >>1)){
            Node node=this.head;
            for(int i=0;i<index;i++){
                node=node.next;
            }
            return node;
        }else{
            Node node=tail;
            for(int i=size-1;i>index;i--){
                node=node.prev;
            }
            return  node;
        }
}
    @Override
    public int size() {
        return size;
    }

    @Override
    public E remove(int index) {
        chickIndex(index);
        Node<E> node =getNode(index);
        E item=node.item;
        if(node.prev==null){
            this.head=node.next;
        }else{
            node.prev.next=node.next;
        }
        if(node.next==null){
            tail=node.prev;
        }
        else {
            node.next.prev=node.prev;
        }
        node.prev=null;
        node.item=null;
        node.next=null;
        
        size--;
        return item;

    }

    public static void main(String[] args) {
        MyDoubleLinkedList<String > m=new MyDoubleLinkedList<>();
        m.add("74");
        m.add("11");
        m.add("215");
        m.add("237");
        m.add("lierqing");
        m.add("127");
        System.out.println(m.size);
        System.out.println(m.size());
        System.out.println(m.remove(0));
        System.out.println(m.size);
        for(int i=0;i<m.size;i++){
            System.out.println(m.get(i));
        }
    }


}

老师，最后为啥会出现异常啊，我找了半天没看明白

package com.baizhan.test;

public class MuLinkedList1<E> implements MyList<E>{
    class Node<E>{
        E item;
        Node next;

        public Node(E item, Node next) {
            this.item = item;
            this.next = next;
        }
    }
    private Node head;
    private  int size;
    @Override
    public void add(E element) {
        Node<E> node=new Node<>(element,null) ;
        Node tail=getTail();
        if(tail==null){
           head=node;
        }else{
            tail.next=node;
        }
        size++;
    }
  private  Node getTail(){

        if(this.head==null){
            return null;
        }else{
            Node node=head;
           for(int i=0;i<size-1;i++){
               if(node.next==null) break;
               node=node.next;
           }
           return  node;
        }

  }
    @Override
    public E get(int index) {
        chickIndex(index);
        Node<E> node=getNode(index);
        return node.item;
    }
    public void chickIndex(int index){
     if(!(index>0&&index<size)) {
         throw new IndexOutOfBoundsException("Index:"+index+"size"+size);
     }
}
private Node getNode(int index){
        Node<E> node=head;
        for(int i=0;i<index;i++){
            node=node.next;
        }
        return node;
}
    @Override
    public int size() {
        return size;
    }

    @Override
    public E remove(int index) {
        chickIndex(index);
        Node<E> node=this.getNode(index);
        E item=node.item;
        if(this.head==node){
           this.head=node.next;
        }else{
            Node<E> temp=head;
            for(int i=0;i<index-1;i++){
                temp=temp.next;
            }
            temp.next=node.next;
             node.next = null;
        }

        this.size--;
        return item;
    }

    public static void main(String[] args) {
        MuLinkedList1<String> my=new MuLinkedList1<>();
        my.add("aaa");
        my.add("bbb");
        my.add("ccc");
        my.add("ddd");
        my.add("eee");
        my.add("fff");
        System.out.println(my.size);
        System.out.println(my.remove(4));
        for(String a:my){
            
        }
    }
}

老师，为啥for each循环会出错

package com.baizhan.test;

public class MuLinkedList1<E> implements MyList<E>{
    class Node<E>{
        E item;
        Node next;

        public Node(E item, Node next) {
            this.item = item;
            this.next = next;
        }
    }
    private Node head;
    private  int size;
    @Override
    public void add(E element) {
        Node<E> node=new Node<>(element,null) ;
        Node tail=getTail();
        if(tail==null){
           head=node;
        }else{
            tail.next=node;
        }
        size++;
    }
  private  Node getTail(){

        if(this.head==null){
            return null;
        }else{
            Node node=head;
           for(int i=0;i<size-1;i++){
               if(node.next==null) break;
               node=node.next;
           }
           return  node;
        }

  }
    @Override
    public E get(int index) {
        chickIndex(index);
        Node<E> node=getNode(index);
        return node.item;
    }
    public void chickIndex(int index){
     if(!(index>0&&index<size)) {
         throw new IndexOutOfBoundsException("Index:"+index+"size"+size);
     }
}
private Node getNode(int index){
        Node<E> node=head;
        for(int i=0;i<index;i++){
            node=node.next;
        }
        return node;
}
    @Override
    public int size() {
        return size;
    }

    @Override
    public E remove(int index) {
        chickIndex(index);
        Node<E> node=this.getNode(index);
        E item=node.item;
        if(this.head==node){
           this.head==node.next;
        }else{
            Node<E> temp=head;
            for(int i=0;i<index-1;i++){
                temp=temp.next;
            }
            temp.next=node.next;
             node.next == null;
        }
       
        this.size--;
        return item;
    }
}

老师，这两个地方为啥会报错

那如果通过命令行执行程序要怎么给定args

老师，赋值不是等号右边赋给左边吗，左边也可以赋给右边吗