problem in simple chat application.

[Punit Jain]

hello i m trying to write a chat application..
but i m getting few errors in the code, here is the code:

Server1.java

import java.net.*;
import java.io.*;
public class Server1 implements Runnable
{	
	ServerSocket ss;
	Socket socket;
	PrintStream ps;
	BufferedReader br, kb;
	Thread thread;
	public Server1()
	{
		try{
			ss = new ServerSocket(1111);
			
		}	
		catch(Exception e)
		{
			System.out.println("socket Could not be created");
		}
	thread = new Thread(this);
	thread.start();
	}
	
	public static void main(String agrs[]) throws Exception
	{
		new Server1();
	}
	public void run() {
		try
		{
		socket = ss.accept();
		System.out.println("Connection Established");								

		ps = new PrintStream(socket.getOutputStream());
		br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
		kb = new BufferedReader(new InputStreamReader(System.in));
		while(true)
		{
			String str,str1;
			while((str = br.readLine())!=null)
			{
				System.out.println(str);
				str1 = kb.readLine();
				ps.println(str1);
			}		
		}	
		}
		catch(Exception e)
		{
			System.out.println("Exception Occured "+e);
		}
		finally
		{
			try{
			kb.close();
			br.close();
			ps.close();
			socket.close();
			ss.close();
			}
			catch(Exception ee)
			{	
				System.out.println("Exception Occured "+ee);
			}
		}
		
	}
}

Client.java

import java.io.*;
import java.net.*;
public class Client
{

	public static void main(String agrs[]) throws Exception
	{
		Socket s = new Socket("192.168.1.6",1111);		
		DataOutputStream dos = new DataOutputStream(s.getOutputStream());
		BufferedReader br = new BufferedReader(new InputStreamReader(s.getInputStream()));
		BufferedReader kb = new BufferedReader(new InputStreamReader(System.in));
		String str,str1;
		while(!(str = kb.readLine()).equals("exit"))
		{
			dos.writeBytes(str+"\n");		
			str1 = br.readLine();
			System.out.println(str1);	
		}
		dos.close();	
		br.close();
		kb.close();
		s.close();
	}
}

The first problem i m getting is, i am able to connect to my network only (i mean able to communicate with those machines which are in my network/same network), how do i connect to others networks??
The second problem is i can communicate only to one machine/client at a time, if other is trying to run client.java (shows no error), but not able to communicate??

how do i solve these two problems??

[Jeff Verdegan]

Punit Jain wrote:
The first problem i m getting is, i am able to connect to my network only (i mean able to communicate with those machines which are in my network/same network), how do i connect to others networks??

If the host you're connecting to isn't on your LAN, then either it has to have a public IP address, or it has to be behind a router that has a public IP address and that is doing port-forwarding to that host.

Private Network
Port Forwarding

Note that the normal way to run a chat application isn't to have all the participants directly connect to each other. Rather, they all connect to a central server that does have a public IP address, and that server acts as a relay for the messages.

[Jeff Verdegan]

Punit Jain wrote:
The second problem is i can communicate only to one machine/client at a time, if other is trying to run client.java (shows no error), but not able to communicate??

What do you mean? What exact problem are you having if you try to run two clients? I notice that your server only allows one connection over its lifetime. Is that what you're asking about? How to connect multiple clients to the same server?

A server is usually structured something like:

while (!done()) {
  Socket socket = ss.accept();
  MySession session = new MySession(socket);
  // create 2 new threads to handle the session--1 for read, 1 for write--or submit it to a pool
}

[Punit Jain]

How to connect multiple clients to the same server?

yes i mean by this.

[Jeff Verdegan]

Punit Jain wrote:

How to connect multiple clients to the same server?

yes i mean by this.

And did you read the rest of my post? Do you understand what you need to do now?

[Punit Jain]

yes i read, but i don't understand, i need more explanation..

[Jeff Verdegan]

Punit Jain wrote:yes i read, but i don't understand, i need more explanation..

That is addressed in your new thread: https://coderanch.com/t/572867/sockets/java/do-port-forwarding-java