static public void main(String args[]) throws Exception {
        if (args.length <= 0) {
            System.err.println("Usage: java MultiPortEcho port [port port ...]");
            System.exit(1);
        }

        int ports[] = new int[args.length];

        for (int i = 0; i < args.length; ++i) {
            ports[i] = Integer.parseInt(args[i]);
        }

        new NIOEchoServer(ports);
    }