JavaFx - Validating Numeric Only Text Field

Earlier, I posted about validating IP in a Text Field. Thought of sharing information about Numeric Only validation too. So, its pretty simple. Here are some lines of codes

1. @FXML
    private TextField port;

2.  if (!validatePort(port.getText())) {
                showDialog("Invalid Port");
            }

3.  public boolean validatePort(final String port) {
        Pattern pattern;
        Matcher matcher;
        String PORT_PATTERN
                = "^([0-9]+)$";
        pattern = Pattern.compile(PORT_PATTERN);
        matcher = pattern.matcher(port);
        return matcher.matches();
    }