Java

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

public class Room implements Runnable{
	public void run(){
		ServerSocket serversocket;
		Socket socket;
		Clients client = new Clients();
		try{
			// Created a socket in which clients can connect to.
			serversocket = new ServerSocket(7776);
			// Waits for a client to connect to the server //	
			while(true){
				socket = serversocket.accept();
				System.out.println("Client connected" + socket);
				// Starts their thread
				client.newThread(socket);
			}
		}catch(IOException e){
			System.out.println(e);
		}
	}
	public static void main(String[] args){
		(new Thread(new Room())).start();
	}
}

import java.io.BufferedReader;
import java.io.IOException;
import java.net.Socket;

public class Clients implements Runnable{
	Socket socket1;
	public void run(){
		Socket socket2 = socket1;
		Users userfunction = new Users();
		BufferedReader bf;
		bf = userfunction.addStream(socket2);
		while(true){
			// Receives a Message.
			try{
				String out = bf.readLine();
				System.out.println(out);
				if(out != null)
					userfunction.sendMessageALL(out);
				
			}catch(IOException e){
				System.out.println(e);
			}
			try{
				Thread.sleep(10);
			} catch (InterruptedException e) {}
		}
	}
	public void newThread(Socket socket){
		// Creates one thread for ever client, to parse the socket I sent it to socket1 which is then
		// received in the thread which is taken to socket2..
		socket1 = socket;
		(new Thread(new Clients())).start();
	}
}

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

public class Users {
	ArrayList<BufferedReader> recieveAL = new ArrayList<BufferedReader>();
	ArrayList<PrintWriter> sendAL = new ArrayList<PrintWriter>();
	// Creates the BufferedReader and PrintWriter then returns the Reader since the Writer it maintained in the class for the sendMessageAll method.
	public BufferedReader addStream(Socket socket){
		BufferedReader br;
		PrintWriter pw;
		try{
			br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
			pw = new PrintWriter(socket.getOutputStream(), true);
			recieveAL.add(br);
			sendAL.add(pw);
			return br;
		}catch(IOException e){
			e.printStackTrace();
		}
		return null;
	}
	// send a message to everyone
	public void sendMessageALL(String send){
		if(send != null){
			for(int x = 0; x < sendAL.size(); x++){
				PrintWriter pw = sendAL.get(x);
				pw.println(send);
				pw.close();
			}
		}
	}
	// Send a message to one person
	public void sendMessage(String send,int x){
		PrintWriter pw = sendAL.get(x);
		pw.println(send);
		pw.close();
	}
}

if(ca.A() == -1) {
    //Do stuff when exception occurred
}

public void B() {
    CA ca = new CA();

    try {
        ca.A();
    } catch(ExceptionThrownFromCA e) {
        //Do your stuff
    }
}