如何在 JavaFX 中切换场景

我已经查看了很多页面以尝试找出如何切换场景，但我没有成功。

我有一个计算器，我的目标是选择一个菜单选项来更改计算器（即：基本计算器和科学计算器）。现在我只是在测试，所以这是我到目前为止与这个问题相关的代码（我正在使用 Scene Builder）：

 @FXML private MenuItem basic;
@FXML private MenuItem testSwitch;

public static void main(String[] args)
{
    Application.launch( args );

}
@Override
public void start(Stage primaryStage) throws Exception
{
   Parent pane = FXMLLoader.load(
           getClass().getResource( "calculator.fxml" ) );

   Scene scene = new Scene( pane );
   primaryStage.setScene(scene);
   primaryStage.setTitle( "Calculator" );
   primaryStage.show();

}
@FXML
public void handleMenuOption(ActionEvent e)
{
    if(e.getSource()==basic)
    {
        changeScene("calculator.fxml");
    }
    else if(e.getSource()==testSwitch)
    {
        changeScene("TestSwitch.fxml");
    }
}
public void changeScene(String fxml)
{
    //this prints out
    System.out.println(fxml);
}

编辑我已经尝试了很多东西。无论如何，我总是得到这个 NullPointerException。我觉得这可能与在场景生成器中设置某些东西有关，但我一直无法找到答案

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.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.control.MenuItem.fire(Unknown Source)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.doSelect(Unknown Source)
at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.lambda$createChildren$343(Unknown Source)
at com.sun.javafx.event.CompositeEventHandler$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.lambda$handleMouseEvent$354(Unknown Source)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(Unknown Source)
at    com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(Unknown Source)
at com.sun.glass.ui.View.handleMouseEvent(Unknown Source)
at com.sun.glass.ui.View.notifyMouse(Unknown Source)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(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)
... 44 more
Caused by: java.lang.NullPointerException
at CalculatorMain.changeScene(CalculatorMain.java:75)
at CalculatorMain.handleMenuOption(CalculatorMain.java:64)
... 53 more

at CalculatorMain.changeScene(CalculatorMain.java:75)
This is at:stage . getScene() . setRoot(pane);

at CalculatorMain.handleMenuOption(CalculatorMain.java:64)
This is at:changeScene ("TestSwitch.fxml");

工作代码：

我尝试使用下面的建议并使用此代码使其工作：

 private Stage stage;

public static void main(String[] args)
{
    Application.launch( args );
}

@Override
public void start(Stage primaryStage) throws Exception
{
    this.stage = primaryStage;
    FXMLLoader loader = new FXMLLoader(getClass()
            .getResource("calculator.fxml"));
    Parent root = (Parent)loader.load();
    BasicCalculatorView controller = (BasicCalculatorView)loader.getController();
    controller.setModel(new BasicCalculatorModelTest(controller));
    controller.setLogic(this);
    primaryStage.setTitle("Calculator");
    primaryStage.setScene(new Scene(root));
    primaryStage.show();
}

public void switchScene(String fxmlFile)
{

    FXMLLoader loader = new FXMLLoader(getClass()
            .getResource(fxmlFile));
    Parent root;
    try
    {
        root = (Parent)loader.load();
        if(fxmlFile.equals("calculator.fxml"))
        {
            BasicCalculatorView controller = (BasicCalculatorView)loader.getController();
            controller.setModel(new BasicCalculatorModelTest(controller));
            controller.setLogic(this);
        }
        else if(fxmlFile.equals("TestSwitch.fxml"))
        {
            TestSwitch controller = (TestSwitch)loader.getController();
            controller.setLogic(this);
        }
        this.stage.setScene(new Scene(root));
    }
    catch (IOException e)
    {
        e.printStackTrace();
    }

}

原文由 Megan 发布，翻译遵循 CC BY-SA 4.0 许可协议

我写了这个控制器来跟踪不同的场景图。

 public class ScreenController {
    private HashMap<String, Pane> screenMap = new HashMap<>();
    private Scene main;

    public ScreenController(Scene main) {
        this.main = main;
    }

    protected void addScreen(String name, Pane pane){
         screenMap.put(name, pane);
    }

    protected void removeScreen(String name){
        screenMap.remove(name);
    }

    protected void activate(String name){
        main.setRoot( screenMap.get(name) );
    }
}

所以我可以写：

 ScreenController screenController = new ScreenController(scene);
screenController.add("calculator", FXMLLoader.load(getClass().getResource( "calculator.fxml" )));
screenController.add("testSwitch", FXMLLoader.load(getClass().getResource( "TestSwitch.fxml" )));
screenController.activate("calculator");

这是全屏应用程序的解决方法，每次舞台切换场景时都会显示 MacOS 全屏过渡。

原文由 MrEbbinghaus 发布，翻译遵循 CC BY-SA 3.0 许可协议

如何在 JavaFX 中切换场景

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