在FXML中创建的JavaFX中设置BorderPane的中心窗格（nullPointerException）

Question

I've spent some time now trying to figure out where my logic is flawed here, and have seen similar questions on here, but for some reason I keep getting a nullPointerException:

public class MainWindowController
    implements Initializable {


    public static final String SCHEDULE_MANAGER = "ScheduleManagerController";
    public static final URL SCHEDULE_MANAGER_FXML = ScheduleManagerController.class.getResource("ScheduleManager.fxml");
    final SwitchableStackPane customStackPane = new SwitchableStackPane();

    @FXML 
    Button btnScheduleManager; // Value injected by FXMLLoader
    BorderPane switchablePane; //Value injected by FXMLLoader


    @Override // This method is called by the FXMLLoader when initialization is complete
    public void initialize(URL fxmlFileLocation, ResourceBundle resources) {
        assert btnScheduleManager != null : "fx:id=\"ScheduleManager\" was not injected: check your FXML file 'HOECTool.fxml'.";
        assert switchablePane != null : "fx:id=\"mainPane\" was not injected: check your FXML file 'HOECTool.fxml'.";


            customStackPane.loadScreen(SCHEDULE_MANAGER, SCHEDULE_MANAGER_FXML);

            switchablePane.setCenter(customStackPane);

    }

This throws a nullPointer exception: switchablePane.setCenter(customStackPane);

Answer 1

Sorted, me being an idiot. This did it:

 @FXML 
    Button btnScheduleManager; // Value injected by FXMLLoader
@FXML
    BorderPane switchablePane; //Value injected by FXMLLoader