Java中的服务器客户端聊天室程序显示地址已在使用中

Question

I am new to networking and I am trying to write the server client program. Still, I keep getting Address already in use and cant chat. A friend of mine run this in his pc and it was working. Can somebody explain to me why I keep getting this error?

Here is the server class:

import java.net.*;
import java.io.*;
class server
{
public static void main(String []args)
{
    try
    {
        ServerSocket serv = new ServerSocket(8001);
        System.out.println("Server up and listening:");
        Socket S = serv.accept();
        InetAddress obj = S.getInetAddress();
        System.out.println("Request coming from:");
        BufferedReader br = new BufferedReader(new InputStreamReader(S.getInputStream()));
        String msg = br.readLine();
        System.out.println("Message recieved:"+msg);
        br.close();
        serv.close();
    }
    catch(Exception e)
    {
        System.out.println(e.getMessage());
    }
}}

Here is the client class:

import java.net.*;
 import java.io.*;
 import java.util.*;
  class client`{
public static void main(String [] args)
{
    Socket s = null;
    BufferedOutputStream bout = null;
    InetAddress obj = null;


    try {

        obj = InetAddress.getByName(args[0]);  
        s = new Socket(obj, 8001);
        String str = new Scanner(System.in).nextLine();
        byte[] arr = str.getBytes();
        bout = new BufferedOutputStream(s.getOutputStream());
        bout.write(arr);
        bout.flush();
        bout.close();
        s.close();
    }
    catch(Exception e)
    {
        System.out.println(e.getMessage());
    }
} }

I appreciate any help you can provide!

Answer 1

使用以下命令确定运行服务器程序的计算机上是否有打开的端口

netstat -nao | find "8001"

Answer 2

You can simply change 8001 to another value. It looks like that it is under use by another program. Depends on your operating system, there are plenty ways to learn which ports are occupied.