我是JavaFX和FXML的新手，我遇到了一个我似乎无法理解的问题，所以希望你们中的一些人能够启发我。
问题似乎发生在我的MainApp.java和我的控制器之间。
public class MainApp extends Application {
private Stage primaryStage;
private AnchorPane overviewPage;
@Override
public void start(Stage primaryStage) {
this.primaryStage = primaryStage;
this.primaryStage.setTitle("");
initStartupLayout();
}
public void initStartupLayout() {
try {
FXMLLoader FXMLLoader = new FXMLLoader();
FXMLLoader.setLocation(getClass().getResource("/view/StandardView.fxml"));
overviewPage = (AnchorPane) FXMLLoader.load();
Scene scene = new Scene(overviewPage);
primaryStage.setScene(scene);
primaryStage.setResizable(false);
primaryStage.sizeToScene();
primaryStage.show();
RootController controller = FXMLLoader.getController();
controller.setMainApp(this);
} catch (IOException e) {
e.printStackTrace();
}
}
public void loadCreateNewRent() {
try {
FXMLLoader loader = new FXMLLoader();
loader.setLocation(MainApp.class.getResource("/view/CreateNewRentView.fxml"));
AnchorPane page = (AnchorPane) loader.load();
// Create the dialog Stage.
Stage dialogStage = new Stage();
dialogStage.setTitle("Opret udlejning");
dialogStage.initModality(Modality.WINDOW_MODAL);
dialogStage.initOwner(primaryStage);
Scene scene = new Scene(page);
dialogStage.setScene(scene);
// Gets the controller and attaches the stage to display
CreateNewRentController controller = loader.getController();
controller.setDialogStage(dialogStage);
// Show the dialog and wait until the user closes it
dialogStage.showAndWait();
} catch (IOException e) {
e.printStackTrace();
}
}
public void loadAdministrateRentals() {
FXMLLoader loader = new FXMLLoader();
loader.setLocation(getClass().getResource("/view/AdministrateRentalsView.fxml"));
loader.load();
overviewPage.getChildren().set(1, FXMLLoader.load(getClass().getResource("/view/AdministrateRentalsView.fxml")));
AdministrateRentalsController controller = (AdministrateRentalsController) loader.getController();
controller.setMainApp(this);
} catch (IOException e) {
e.printStackTrace();
}
}
public void backToInitView() {
try {
FXMLLoader loader = new FXMLLoader();
loader.setLocation(getClass().getResource("/view/AdministrateRentalsView.fxml"));
loader.load();
overviewPage.getChildren().set(1, FXMLLoader.load(getClass().getResource("/view/AdministrateRentalsView.fxml")));
} catch (IOException e) {
e.printStackTrace();
}
}
public void createNewProduct() {
try {
FXMLLoader loader = new FXMLLoader();
loader.setLocation(MainApp.class.getResource("/view/AdministrateRentalsView.fxml"));
overviewPage.getChildren().set(1, FXMLLoader.load(MainApp.class.getResource("/view/C.fxml")));
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
launch(args);
}
}
public class RootController implements Initializable {
private Stage primaryStage;
private MainApp mainApp;
@FXML
public void createLease(ActionEvent event) {
mainApp.loadCreateNewRent();
}
@FXML
public void administrateLease(ActionEvent event) {
mainApp.loadAdministrateRentals();
}
@Override
public void initialize(URL arg0, ResourceBundle arg1) {
// TODO Auto-generated method stub
}
public void setMainApp(MainApp mainApp) {
this.mainApp = mainApp;
}
}
public class AdministrateRentalsController implements Initializable {
private Stage primaryStage;
private MainApp mainApp;
@FXML
public void backToInitScreen(ActionEvent event) {
mainApp.initStartupLayout();
}
@FXML
public void backToStartup(ActionEvent event) {
mainApp.backToInitView();
}
@FXML
public void createNewProduct(ActionEvent event) {
mainApp.createNewProduct();
}
@Override
public void initialize(URL location, ResourceBundle resources) {
// TODO Auto-generated method stub
}
public void setMainApp(MainApp mainApp) {
this.mainApp = mainApp;
}
}
当我在调用administrateLease方法时从StandardView转到AdministrateRentView时，它工作得很好。但是当我试图通过调用backToStartUp方法回到上一个视图时，它会给我一个NullPointerException，我似乎无法弄清楚，堆栈跟踪：
Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at javafx.fxml.FXMLLoader$MethodHandler.invoke(Unknown Source)
at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(Unknown Source)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(Unknown Source)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(Unknown Source)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
at com.sun.javafx.event.EventUtil.fireEventImpl(Unknown Source)
at com.sun.javafx.event.EventUtil.fireEvent(Unknown Source)
at javafx.event.Event.fireEvent(Unknown Source)
at javafx.scene.Node.fireEvent(Unknown Source)
at javafx.scene.control.Button.fire(Unknown Source)
at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(Unknown Source)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(Unknown Source)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(Unknown Source)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(Unknown Source)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(Unknown Source)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(Unknown Source)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(Unknown Source)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(Unknown Source)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(Unknown Source)
at com.sun.javafx.event.EventUtil.fireEventImpl(Unknown Source)
at com.sun.javafx.event.EventUtil.fireEvent(Unknown Source)
at javafx.event.Event.fireEvent(Unknown Source)
at javafx.scene.Scene$MouseHandler.process(Unknown Source)
at javafx.scene.Scene$MouseHandler.access$1500(Unknown Source)
at javafx.scene.Scene.impl_processMouseEvent(Unknown Source)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Unknown Source)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(Unknown Source)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(Unknown Source)
at com.sun.glass.ui.View.handleMouseEvent(Unknown Source)
at com.sun.glass.ui.View.notifyMouse(Unknown Source)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$141(Unknown Source)
at com.sun.glass.ui.win.WinApplication$$Lambda$37/1109371569.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at sun.reflect.misc.Trampoline.invoke(Unknown Source)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at sun.reflect.misc.MethodUtil.invoke(Unknown Source)
... 52 more
Caused by: java.lang.NullPointerException
at Controller.AdministrateRentalsController.backToStartup
(AdministrateRentalsController.java:23)
... 61 more