private boolean isGoodLogin(String login, String password, HashMap currentlyConnectedUsers) {
        if (currentlyConnectedUsers.get(login) == null) {
            File file = new File(userFilePath);
            if (file.exists()) {
                try {

                    BufferedReader br = new BufferedReader(
                            new InputStreamReader(
                            new FileInputStream(file)));
                    String ligne;
                    while ((ligne = br.readLine()) != null) {
                        String[] resultSplit = ligne.split(":");
                        if (login.equals(resultSplit[0]) && password.equals(resultSplit[1])) {
                            return true;
                        }
                    }
                    br.close();
                } catch (Exception e) {
                    System.out.println(e.toString());
                }

            }
            return false;
        } else {
            System.out.println("User with same name already logged in");
            return false;
        }
    }