public void writeMessageToOnlineUser(String forUser, String fromUser, String message) {
        try {
            forUser.replaceAll(" ", "");
            ServerThread correspondingClient = connectedClients.get(forUser);
            correspondingClient.out.writeUTF(fromUser + ": " + message);
            correspondingClient.out.flush();
            System.out.println("for user: " + forUser + " OUTGOING: " + message);
        } catch (IOException ex) {
            Logger.getLogger(ServerThread.class.getName()).log(Level.SEVERE, null, ex);
        }
    }