What is the class to use for server in single server multiclient chat programming

[Shaik Muhammad]

Hi,
I am new to socket programming and working on a miniproject for chat server programming. Four clients are chatting through a server. The server is multithreaded. the client code is :

package ruf;
import java.net.*;
import java.io.*;
public class EchoClient {
 
public static void echoClient(BufferedReader in, PrintStream out) throws IOException{
String keybd;
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

while(true){
keybd = br.readLine();
if(keybd == null){
break;
}

out.println(keybd);
String instr = in.readLine();
System.out.println("Server: "+instr);
}
}


 
public static void main(String[] args){
 
Socket socket = null;
BufferedReader in;
PrintStream out;
try {
 
 
/* Create a socket */
socket = new Socket(InetAddress.getByName("localhost"),9000);
if (socket.isConnected()){
System.out.println("socket is connected");
}
/* Create buffered reader for reading from socket and print stream for writing into socket */
in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
out = new PrintStream(socket.getOutputStream());
 
/* Print into console the details of IP and port onto which the socket is connected */
System.out.println("Connected to "+ socket.getInetAddress()+" : "+socket.getLocalPort());
 
/* Calling the echoClient method to write into socket and read from socket including keyboard inputs */
echoClient(in, out);

if(socket==null){
 
socket.close();
System.out.println("Connection is closed");
} 
}catch (UnknownHostException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

}
 
}

Using Serversocket class makes the server to bounce the message from a client to that same client, not to console of all the clients.What class should be used in server so that the server bounces back the message from one client to the console of all the four clients?

Please help

[edit]Add code tags. CR[/edit]
[ July 24, 2008: Message edited by: Campbell Ritchie ]

[Ulf Dittmer]

Using Serversocket class makes the server to bounce the message from a client to that same client, not to console of all the clients.

The function of a ServerSocket is to communicate with one client at a time, although it can accept multiple connections (as you apparently have implented already).

If you want it to send something to a client that originates from a different client, then you need to put the code to do that in place yourself - that's not something ServerSocket (or any other JRE class) does.

So if a client sends something that the server should send to all clients, store it in a data structure that all threads have access to. Or you could implement a listener scheme using something like the Observer/Observable classes (the clients threads would be the observers, the server thread the observed).

[Campbell Ritchie]

Please Use Code Tags; I have added them so you can see how much easier the code is to read.

Did you really write "if (socket == null) . . . socket.close();"? Don't you mean if (socket != null)?