import java.io.*;
import java.net.*;
import java.util.*;
 
public class Server
{
	ArrayList clientOutputStreams;
 
	public void go()
	{
		clientOutputStreams = new ArrayList();
 
		try
		{
			ServerSocket serverSock = new ServerSocket(4999);
 
			while (true)
			{ // set up the server writer function and then begin at the same
			  // the listener using the Runnable and Thread
				Socket clientSock = serverSock.accept();
				PrintWriter writer = new PrintWriter(clientSock.getOutputStream());
				clientOutputStreams.add(writer);
 
				// use a Runnable to start a 'second main method that will run
				// the listener
				Thread listener = new Thread(new ClientHandler(clientSock));
				listener.start();
				System.out.println("got a connection");
			} // end while
		} // end try
		catch (Exception ex)
		{
			System.out.println("error making a connection");
		} // end catch
 
	} // end go()
 
	public class ClientHandler implements Runnable
	{
		BufferedReader reader;
		Socket sock;
 
		public ClientHandler(Socket clientSocket)
		{ // new inputStreamReader and then add it to a BufferedReader
 
			try
			{
				sock = clientSocket;
				InputStreamReader isReader = new InputStreamReader(sock.getInputStream());
				reader = new BufferedReader(isReader);
			} // end try
			catch (Exception ex)
			{
				System.out.println("error beginning StreamReader");
			} // end catch
 
		} // end ClientHandler()
 
		public void run()
		{
			String message;
 
			try
			{
				while ((message = reader.readLine()) != null)
				{
					System.out.println("read" + message);
					tellEveryone(message);
				} // end while
			} // end try
			catch (Exception ex)
			{
				System.out.println("lost a connection");
			} // end catch
		} // end run()
	} // end class ClientHandler
 
	public void tellEveryone(String message)
	{ // sends message to everyone connected to server
		Iterator it = clientOutputStreams.iterator();
 
		while (it.hasNext())
		{
			try
			{
				PrintWriter writer = (PrintWriter) it.next();
				writer.println(message);
				writer.flush();
			} // end try
			catch (Exception ex)
			{
				System.out.println("error telling everyone");
			} // end catch
		} // end while
	} // end tellEveryone()
} // end class Server