public static void main(String args[]) { int port; String host; if (args.length == 1) { try { port = Integer.parseInt(args[0]); doEcho(port); } catch (IOException io_ex) { io_ex.printStackTrace(); System.exit(1); } catch (NumberFormatException num_ex) { num_ex.printStackTrace(); System.exit(1); } } else if (args.length == 2) { try { host = args[0]; port = Integer.parseInt(args[1]); UDPEcho ut = new UDPEcho(host, port); Thread thread = new Thread(ut); thread.start(); BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); String s; System.out.print("Enter datagram:"); s = in.readLine(); while (s != null) { ut.send(s); try { Thread.currentThread().sleep(100); } catch (InterruptedException i_ex) { } System.out.print("Enter datagram:"); s = in.readLine(); } System.exit(1); } catch (IOException io_ex) { io_ex.printStackTrace(); System.exit(1); } catch (NumberFormatException num_ex) { num_ex.printStackTrace(); System.exit(1); } } else { usage(); } }