Java chat program

[lintwurm]

Hey guys...

So I have probably written the most useless program ever...
This is supposed to be a chat program with multiple clients connecting to one server.
The problem being that the first client connects and can send to the server without problems.
But when you connect two clients, the server doesn't receive anything from the second client until the first client disconnects, but it gets all the messages from the first client... Also, The server doesn't send the message being passed to it to all the rest of the clients.
What I am thinking is that I need a new thread for all clients, but coding it is just taking me forever. Apparently I just fail that hard ^_^

Can anyone please just take a look at it and tell me what to do?

My code for the server:

import java.net.*;
import java.io.*;
public class myFrame
{
	private static ServerSocket serverSocket;
	private static Socket clientSocket;
	private static BufferedReader bufferedReader;
	private static String inputLine;
	private Thread thread = null;
	public static void main(String[] args)
	{

		// Wait for client to connect on 63400
		try
		{
			serverSocket = new ServerSocket(63400);
			clientSocket = serverSocket.accept();
			// Create a reader
			bufferedReader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
			// Get the client message
			while((inputLine = bufferedReader.readLine()) != null)
				System.out.println(inputLine);
		}
		catch(IOException e)
		{
			System.out.println(e);
		}
	}
}

And now for the client...

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

public class myFrame
{
	private static Socket socket;
	private static PrintWriter printWriter;
	public static void main(String[] args)
	{
		try
		{
			socket = new Socket("localhost",63400);
			printWriter = new PrintWriter(socket.getOutputStream(),true);
			String Name;
			String message = "";
			Scanner in = new Scanner(System.in);
			System.out.println("Please enter your name for the chat.");
			Name = in.nextLine();
			System.out.println("You may now start chatting away!");
			while(message.compareTo("exit") != 0)
			{
				message = in.nextLine();	
				printWriter.println(Name + " : " + message);
			}
		}
		catch(Exception e)
		{
			System.out.println(e);
		}
	}
}

Thank you very much for your time
^_^

[lintwurm]

Ok...

I have changed this thing so it can work on a browser using an applet for the client

My server class using Netbeans looks like this:

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package server;

/*
 *
 * @author lintwurm
 */
import java.io.*;
import java.net.*;
import java.util.*;
public class Server
{
	// The ServerSocket we'll use for accepting new connections
	private ServerSocket ss;
	// A mapping from sockets to DataOutputStreams. This will
	// help us avoid having to create a DataOutputStream each time
	// we want to write to a stream.
	private Hashtable outputStreams = new Hashtable();
	// Constructor and while-accept loop all in one.
	public Server( int port ) throws IOException
	{
		// All we have to do is listen
		listen( port );
	}
	private void listen( int port ) throws IOException
	{
		// Create the ServerSocket
		ss = new ServerSocket( port );
		// Tell the world we're ready to go
		System.out.println( "Listening on "+ss );
		// Keep accepting connections forever
		while (true)
		{
			// Grab the next incoming connection
			Socket s = ss.accept();
			// Tell the world we've got it
			System.out.println( "Connection from "+s );
			// Create a DataOutputStream for writing data to the
			// other side
			DataOutputStream dout = new DataOutputStream( s.getOutputStream() );
			// Save this stream so we don't need to make it again
			outputStreams.put( s, dout );
			// Create a new thread for this connection, and then forget
			// about it
			new ServerThread( this, s );
		}
	}
	// Get an enumeration of all the OutputStreams, one for each client
	// connected to us
	Enumeration getOutputStreams()
	{
		return outputStreams.elements();
	}
	// Send a message to all clients (utility routine)
	void sendToAll( String message )
	{
		// We synchronize on this because another thread might be
		// calling removeConnection() and this would screw us up
		// as we tried to walk through the list
		synchronized( outputStreams )
		{
		// For each client ...
			for (Enumeration e = getOutputStreams(); e.hasMoreElements(); )
			{
				// ... get the output stream ...
				DataOutputStream dout = (DataOutputStream)e.nextElement();
				// ... and send the message
				try
				{
					dout.writeUTF( message );
				}
				catch( IOException ie )
				{
					System.out.println( ie );
				}
			}
		}
	}
	// Remove a socket, and it's corresponding output stream, from our
	// list. This is usually called by a connection thread that has
	// discovered that the connectin to the client is dead.
	void removeConnection( Socket s )
	{
		// Synchronize so we don't mess up sendToAll() while it walks
		// down the list of all output streamsa
		synchronized( outputStreams )
		{
			// Tell the world
			System.out.println( "Removing connection to "+s );
			// Remove it from our hashtable/list
			outputStreams.remove( s );
			// Make sure it's closed
			try
			{
				s.close();
			}
			catch( IOException ie )
			{
				System.out.println( "Error closing "+s );
				ie.printStackTrace();
			}
		}
	}
	// Main routine
	// Usage: java Server <port>
	static public void main( String args[] ) throws Exception
	{
		// Get the port # from the command line
		int port = 80;
		// Create a Server object, which will automatically begin
		// accepting connections.
		new Server( port );
	}
}

Then I have another class called ServerThread that looks like this:

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package server;

/*
 *
 * @author s28339208
 */
import java.io.*;
import java.net.*;

public class ServerThread extends Thread
{
	// The Server that spawned us
	private Server server;
	// The Socket connected to our client
	private Socket socket;
	// Constructor.
	public ServerThread( Server server, Socket socket )
	{
		// Save the parameters
		this.server = server;
		this.socket = socket;
		// Start up the thread
		start();
	}
	// This runs in a separate thread when start() is called in the
	// constructor.
	public void run()
	{
		try
		{
			// Create a DataInputStream for communication; the client
			// is using a DataOutputStream to write to us
			DataInputStream din = new DataInputStream( socket.getInputStream() );
			// Over and over, forever ...
			while (true)
			{
				// ... read the next message ...
				String message = din.readUTF();
				// ... tell the world ...
				System.out.println( "Sending "+message );
				// ... and have the server send it to all clients
				server.sendToAll( message );
			}
		}
		catch( EOFException ie )
		{
			// This doesn't need an error message
		}
		catch( IOException ie )
		{
			// This does; tell the world!
			ie.printStackTrace();
		}
		finally
		{
			// The connection is closed for one reason or another,
			// so have the server dealing with it
			server.removeConnection( socket );
		}
	}
}

Now for the client...

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package client;

/*
 *
 * @author s28339208
 */
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
public class Client extends Panel implements Runnable
{
	// Components for the visual display of the chat windows
	private TextField tf = new TextField();
	private TextArea ta = new TextArea();
	// The socket connecting us to the server
	private Socket socket;
	// The streams we communicate to the server; these come
	// from the socket
	private DataOutputStream dout;
	private DataInputStream din;
	// Constructor
	public Client( String host, int port )
	{
		// Set up the screen
		setLayout( new BorderLayout() );
		add( "North", tf );
		add( "Center", ta );
		// We want to receive messages when someone types a line
		// and hits return, using an anonymous class as
		// a callback
		tf.addActionListener( new ActionListener()
		{
			public void actionPerformed( ActionEvent e )
			{
				processMessage( e.getActionCommand() );
			}
		} );
		// Connect to the server
		try
		{
			// Initiate the connection
			socket = new Socket( "localhost", 80 );
			// We got a connection! Tell the world
			System.out.println( "connected to "+socket );
			// Let's grab the streams and create DataInput/Output streams
			// from them
			din = new DataInputStream( socket.getInputStream() );
			dout = new DataOutputStream( socket.getOutputStream() );
			// Start a background thread for receiving messages
			new Thread( this ).start();
		}
		catch( IOException ie )
		{
			System.out.println( ie );
		}
	}
	// Gets called when the user types something
	private void processMessage( String message )
	{
		try
		{
			// Send it to the server
			dout.writeUTF( message );
			// Clear out text input field
			tf.setText( "" );
		} catch( IOException ie ) { System.out.println( ie ); }
	}
	// Background thread runs this: show messages from other window
	public void run()
	{
		try
		{
			// Receive messages one-by-one, forever
			while (true)
			{
				// Get the next message
				String message = din.readUTF();
				// Print it to our text window
				ta.append( message+"\n" );
			}
		}
		catch( IOException ie )
		{
			System.out.println( ie );
		}
	}
}

And the applet part.

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package client;

/*
 *
 * @author s28339208
 */
import java.applet.*;
import java.awt.*;
public class ClientApplet extends Applet
{
	public void init()
	{
		String host = getParameter( "localhost" );
		int port = 80;
		setLayout( new BorderLayout() );
		add( "Center", new Client( host, port ) );
	}
}

now for the stupid part...
I created a html file that calls the ClientApplet.class (as I think I should)
but the browser just says that it has an error instead of displaying the applet. Am I being stupid and calling the wrong class?

This is the exact output I get from the browser:

java.lang.NoClassDefFoundError: ClientApplet (wrong name: client/ClientApplet)
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClassCond(Unknown Source)
	at java.lang.ClassLoader.defineClass(Unknown Source)
	at java.security.SecureClassLoader.defineClass(Unknown Source)
	at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
	at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source)
	at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
Exception: java.lang.NoClassDefFoundError: ClientApplet (wrong name: client/ClientApplet)

And one more question,
Will this work if I run the server from Netbeans and the clients just html? Or is this why the browser is complaining?

Thank you for your time
^_^

[Deadlock]

You Just need to use a single thread for each client because obviously you cant ask the server to handle more than 1 client at a time without multi-tasking. The server should create a clientThread whenever it has a new connection.