1-) Java - Uygulama açıksa tekrar açmaz

private static final int PORT = 9999;

    private static ServerSocket socket;

    private static void checkIfRunning() throws UnknownHostException, IOException {

        try {

            //Bind to localhost adapter with a zero connection queue

            socket = new ServerSocket(PORT, 0, InetAddress.getByAddress(new byte[]{127, 0, 0, 1}));

        } catch (BindException e) {

            System.err.println("Already running.");

            System.exit(1);

        } catch (IOException e) {

            System.err.println("Unexpected error.");

            e.printStackTrace();

            System.exit(2);

        }

    }