public static void main(String[] args) {
        stringWorld = new StringWorld();
        try {
            ServerSocket serverSocket = new ServerSocket(5000);
            while(true) {
                Socket socket = serverSocket.accept();
                System.out.println("accept connection " + serverSocket.getInetAddress());
                new ConnectionThread(socket, getStringWorld()).start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }