When the program starts, it should open a server socket to listen for connection

Question

When the program starts, it should open a server socket to listen for connections on port 8081. When a client connection is received, the program should create a new thread to handle the connection. The worker thread should read a single line of text from the connection (up to the newline character), write the line back to the client connection, and close the connection. The program should accept new connections until it is forcibly shut down. The program must be multi-threaded and be capable of responding to multiple requests at once. Helpful Hints: Use the java.net.ServerSocket class to open a port and listen for new connections (see chapter 3 of the textbook for more information). Use the java.net.ServerSocket.accept() method to accept a new client connection. You can read from and write to the data streams in java.net.ServerSocket.getOutputStream() and java.net.ServerSocket.getInputStream() just as if they were files or standard input/output. I created the following program but I keep getting three errors that I do not know hot to correct. import java.net.*; //error here import java.io.*; //error here public class mserver { public static Socket s[] = new Socket[10]; public static void main(String a[]) { int i=0; try { ServerSocket ss = new ServerSocket(8081); while(true) { s[i] = ss.accept(); BufferedReader br = new BufferedReader(new InputStreamReader(s[i].getInputStream())); String msg; try { reqhandler req = new reqhandler(s[i],i); i++; Thread t = new Thread(req); t.start(); } catch(Exception e) { System.out.println(e); } } } catch(Exception e) { System.out.println(e); } } } class reqhandler implements Runnable { public int n; public Socket s; public reqhandler(Socket soc,int i) { s = soc; n = i; } public void run() { String msg = ""; BufferedReader br; PrintWriter pw; try { br = new BufferedReader(new InputStreamReader(s.getInputStream())); msg = br.readLine(); pw = new PrintWriter(new OutputStreamWriter(mserver.s[n].getOutputStream())); pw.println(msg+" "); pw.flush(); s.close(); } catch(Exception e) { } } } client side program //error here import java.net.*; // error here import java.io.*; // error here public class mclient { public static void main(String a[]) { BufferedReader in,br; PrintWriter pw; try { Socket s = new Socket("localhost",8081); in = new BufferedReader(new InputStreamReader(System.in)); String msg; pw = new PrintWriter(new OutputStreamWriter(s.getOutputStream())); msg = in.readLine(); pw.println(msg); pw.flush(); br = new BufferedReader(new InputStreamReader(s.getInputStream())); msg = br.readLine(); System.out.println(msg); } catch(Exception e) { System.out.println(e); } } } I keep getting error codes: error: class, interface, or enum expected client side program ^ error: class, interface, or enum expected import java.io.*; ^ 2 errors Thank you

Explanation / Answer

Mserver.java

//One to many server program

import java.io.*;
import java.net.*;
import java.util.*;

public class Mserver
{
public static Socket s[]=new Socket[10];
public static String user[]=new String[10];
public static int total;

public static void main(String []args)
{
int i=0;

try
{
   ServerSocket ss=new ServerSocket(2016);
System.out.println(" Server Started ..... ");
   while(true)
   {
    s[i]=ss.accept();
    BufferedReader br=new BufferedReader(new InputStreamReader(s[i].getInputStream()));
    String msg=br.readLine();
    user[i]=msg;
    System.out.println(msg +" Connected To Server ");
  
    try
    {
     ReqHandler req=new ReqHandler(s[i],i);
     total=i;
     i++;
     Thread t=new Thread(req);
     t.start();
    }

    catch(Exception e)
    {
     System.out.println(e + " Client Disconnected ");
    }
   }
}

catch(Exception e)
{
   System.out.println(e);
}
}
}

ReadData.java

//ReadData class for One to many chat application

import java.io.*;
import java.net.*;

class ReadData implements Runnable
{
public Socket s;

public ReadData(Socket s)
{
this.s=s;
}

public void run()
{
BufferedReader br;
try
{
   while(true)
   {
    br=new BufferedReader(new InputStreamReader(s.getInputStream()));
    String msg=br.readLine();
    System.out.println(msg);
   }
}
catch(Exception e)
{
   System.out.println(e.getMessage());
}
}
}

ReqHandler.java

//ReqHandler class for One to many chat application

import java.net.*;
import java.io.*;

class ReqHandler implements Runnable
{
public int n;
public Socket s;

public ReqHandler(Socket soc,int i)
{
s=soc;
n=i;
}

public void run()
{
BufferedReader br;
PrintWriter pw;
try
{
   while(true)
   {
    br=new BufferedReader(new InputStreamReader(s.getInputStream()));
    String msg=br.readLine();

    //if(msg.equals("quit") || msg==null)
if(msg==null)
{
    Mserver.total--;
throw new Exception( " Client is Disconnected From Server ");
}
    else
    System.out.println(" " + Mserver.user[n]+"-->" + (n+1) +"/" + (Mserver.total+1) +"::"+msg);

    if(Mserver.total==-1)
    {
     System.out.println("server disconnected");
     System.exit(0);
    }
  
    for(int k=0;k<=Mserver.total;k++)
    {
     if(!Mserver.user[k].equals(Mserver.user[n]) && (!msg.equals("quit")))
     {
      pw=new PrintWriter(new OutputStreamWriter(Mserver.s[k].getOutputStream()));
      pw.println(Mserver.user[n]+"=>"+msg+" ");
      pw.flush();
     }
    }

   }
}

catch(Exception e)
{
   System.out.println(e.getMessage());
}
}
}

Mclient.java

//One to many chat application

import java.net.*;
import java.io.*;

public class Mclient
{
public static void main(String []args)
{
BufferedReader in;
PrintWriter pw;
try
{
   Socket s=new Socket("localhost",2016);
   System.out.println("Enter name:");
   in=new BufferedReader(new InputStreamReader(System.in));
   String msg=in.readLine();
   pw=new PrintWriter(new OutputStreamWriter(s.getOutputStream()));
   pw.println(msg+" ");
   pw.flush();

   while(true)
   {
    ReadData rd=new ReadData(s);
    Thread t=new Thread(rd);
    t.start();
    msg=in.readLine();
    if(msg.equals("quit"))
            System.exit(0);
    pw.println(msg);
    pw.flush();
   }
}

catch(Exception e)
{
   System.out.println(e);
}
}
}

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