javafx encountered pit

Use Controller controls defined mapping between class way, you need to pay attention to:
1.Controller class field defines the name of the file should be consistent with fxml control id, the event listener method shall be the same xxxxx "# xxxxx" in the onAction =, fields, methods require modification by @FXML comment.
2. Add the root fxml fx file: controller = "xxxxx" indicates the layout file which corresponds to a Controller.

*** javafx use in a radiobutton ***

 final ToggleGroup group = new ToggleGroup();

            RadioButton rb11 = new RadioButton("选中");
            rb11.setToggleGroup(group);
            rb11.setUserData(1);

            RadioButton rb21 = new RadioButton("未选");
            rb21.setToggleGroup(group);
            rb21.setUserData(0);

            // 选中某个单选框时输出选中的值
            group.selectedToggleProperty().addListener(
                    new ChangeListener<Toggle>() {
                        public void changed(
                                ObservableValue<? extends Toggle> ov,
                                Toggle old_toggle, Toggle new_toggle) {
                            if (group.getSelectedToggle() != null) {
                                System.out.println(group.getSelectedToggle()
                                        .getUserData());
                            }
                        }
                    });