MultiThreaded Chat Client program in Java Language

Code :
/*************Start program Server************************************************/
/*This is the server for the MultiThreadedChatClient program that,I wrote basically it gives u a good understanding of how sockets work in java
Author: Sumit Kumar Pundhir
email:sumit123go@gmail.com
*/
import java.io.*;
import java.net.*;
public class MultiThreadChatServer{

    // Declaration section:
    // declare a server socket and a client socket for the server
    // declare an input and an output stream

    static  Socket clientSocket = null;
    static  ServerSocket serverSocket = null;

    // This chat server can accept up to 10 clients' connections

    static  clientThread t[] = new clientThread[10];

    public static void main(String args[]) {

// The default port

int port_number=8888;

if (args.length < 1)
   {
System.out.println("Usage: java MultiThreadChatServer
"+
  "Now using port number="+port_number);
   } else {
port_number=Integer.valueOf(args[0]).intValue();
   }

// Initialization section:
// Try to open a server socket on port port_number (default 8888)
// Note that we can't choose a port less than 1023 if we are not
// privileged users (root)

        try {
   serverSocket = new ServerSocket(port_number);
        }//try
        catch (IOException e)
   {System.out.println(e);}

// Create a socket object from the ServerSocket to listen and accept
// connections.
// Open input and output streams for this socket will be created in
// client's thread since every client is served by the server in
// an individual thread

//can use a for loop to control the number of clients
//I have used the while so that we can have unlimited number of clients
while(true){
   try {
clientSocket = serverSocket.accept();
new clientThread(clientSocket,t).start();
break;
}//try

   catch (IOException e){
System.out.println(e);}
}
    }
} //class

// This client thread opens the input and the output streams for a
particular client,
// ask the client's name, informs all the clients currently connected
to
the
// server about the fact that a new client has joined the chat room,
// and as long as it receive data, echos that data back to all other
clients.
// When the client leaves the chat room this thread informs also all
the
// clients about that and terminates.

class clientThread extends Thread{

    DataInputStream is = null;
    PrintStream os = null;
    Socket clientSocket = null;
    clientThread t[];

    public clientThread(Socket clientSocket, clientThread[] t){
this.clientSocket=clientSocket;
        this.t=t;
    }

    public void run()
    {
String line;
        String name;
try{
   is = new DataInputStream(clientSocket.getInputStream());
   os = new PrintStream(clientSocket.getOutputStream());
   os.println("Enter your name.");
   name = is.readLine();
   os.println("Hello "+name+" to our chat room.
To leave enter /quit
in
a new line");
   for(int i=0; i<=9; i++)
if (t[i]!=null && t[i]!=this)
   t[i].os.println("*** A new user "+name+" entered the chat room
!!!
***" );
   while (true) {
line = is.readLine();
                if(line.startsWith("/quit")) break;
for(int i=0; i<=9; i++)
   if (t[i]!=null)  t[i].os.println("<"+name+"> "+line);
   }
   for(int i=0; i<=9; i++)
if (t[i]!=null && t[i]!=this)
   t[i].os.println("*** The user "+name+" is leaving the chat room
!!!
***" );

   os.println("*** Bye "+name+" ***");

   // Clean up:
   // Set to null the current thread variable such that other client
could
   // be accepted by the server

   for(int i=0; i<=9; i++)
if (t[i]==this) t[i]=null;

   // close the output stream
   // close the input stream
   // close the socket

   is.close();
   os.close();
   clientSocket.close();
}
catch(IOException e){};
    }
}

/*************End program Server**************************************/




/***********************Start Client program************************/

/*This is the client for the MultiThreadedChatServer program that,I
wrote
basically it
gives u a good understanding of how sockets work in java
Author: Sumit Kumar Pundhir
email:sumit123go@gmail.com
*/

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

public class MultiThreadChatClient implements Runnable{

    // Declaration section
    // clientClient: the client socket
    // os: the output stream
    // is: the input stream

    static Socket clientSocket = null;
    static PrintStream os = null;
    static DataInputStream is = null;
    static BufferedReader inputLine = null;
    static boolean closed = false;

    public static void main(String[] args) {

// The default port

int port_number=8888;
        String host="localhost";

if (args.length < 2)
   {
System.out.println("Usage: java MultiThreadChatClient
"+
  "Now using host="+host+", port_number="+port_number);
   } else {
host=args[0];
port_number=Integer.valueOf(args[1]).intValue();
   }
// Initialization section:
// Try to open a socket on a given host and port
// Try to open input and output streams
try {
            clientSocket = new Socket(host, port_number);
            inputLine = new BufferedReader(new
InputStreamReader(System.in));
            os = new PrintStream(clientSocket.getOutputStream());
            is = new DataInputStream(clientSocket.getInputStream());
        } catch (UnknownHostException e) {
            System.err.println("Don't know about host "+host);
        } catch (IOException e) {
            System.err.println("Couldn't get I/O for the connection to
the
host "+host);
        }

// If everything has been initialized then we want to write some data
// to the socket we have opened a connection to on port port_number

        if (clientSocket != null && os != null && is != null) {
            try {

// Create a thread to read from the server

                new Thread(new MultiThreadChatClient()).start();

while (!closed) {
                    os.println(inputLine.readLine());
                }

// Clean up:
// close the output stream
// close the input stream
// close the socket

os.close();
is.close();
clientSocket.close();
            } catch (IOException e) {
                System.err.println("IOException:  " + e);
            }
        }
    }

    public void run() {
String responseLine;

// Keep on reading from the socket till we receive the "Bye" from the
server,
// once we received that then we want to break.
try{
   while ((responseLine = is.readLine()) != null) {
System.out.println(responseLine);
if (responseLine.indexOf("*** Bye") != -1) break;
   }
            closed=true;
} catch (IOException e) {
   System.err.println("IOException:  " + e);
}
    }
}

/***********************End Client program************************************/

We welcome your Suggestions and Advice's for improving the content in the blog.Please Comment your queries also whatever you feel from your side.