/** Called when the user clicks ok. */
  @FXML
  private void handleOk() {
    if (isInputValid()) {
      person.setFirstName(firstNameField.getText());
      person.setLastName(lastNameField.getText());
      person.setStreet(streetField.getText());
      person.setPostalCode(Integer.parseInt(postalCodeField.getText()));
      person.setCity(cityField.getText());
      person.setBirthday(birthdayField.getValue());

      okClicked = true;
      dialogStage.close();
    }
  }