如何在JavaFX中切换场景

问题描述：

我已经浏览了很多页面，尝试了解如何切换场景，但我一直不成功。如何在JavaFX中切换场景

我有一个计算器，我的目标是选择一个菜单选项来改变计算器（即：基本和科学）。现在我只是测试所以这里是我的代码有关这个问题迄今（我使用场景生成器）：

@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); 
}

编辑我已经尝试了不少东西了。无论如何，我总是得到这个NullPointerException。我有一种感觉它可能与场景构建器来设置点事做，但我只是一直没能找到答案

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：

我发挥各地使用下面的建议，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(); 
    } 

}

我发挥各地使用下面的建议，并得到它的工作 – Megan

答

我写了这个控制器来跟踪不同的scenegraphes。

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)); 
    } 
}

因此我可以这样写：

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");

这是一个全屏应用，其中MacOS的全屏过渡表现出每一个阶段切换其现场解决的办法。

答

，而不是切换Scenes，切换根节点上已有Scene

我都试过，但我不断收到一个空指针异常。在收到关于同一件事的两条评论后，我决定发布我的异常消息，参见上文。 – Megan

在您的代码中，您正在混合'Application'和FXML控制器概念。每个有不同的初始化生命周期。 FXML控制器基于依赖注入原则，初始化应该在'init'方法中完成。阅读FXML控制器。你也可以看到下面的内容http://*.com/questions/34785417/javafx-fxml-controller-constructor-vs-initialize-method –

那么我将如何切换场景。我尝试使用init方法并设置一个字符串参数。如果我传递了一个字符串，例如“test”，并使用syso打印出结果，它会打印出测试结果。但如果我传递了一个字符串与FXML文件，并试图设置一个场景，它会给我一个空指针异常 – Megan

答

如果你想改变场景一起去，你会做这样的（注意，舞台是应用程序的成员）：

private Stage primaryStage; 

@Override 
public void start(Stage primaryStage) throws Exception { 
    this.primaryStage = primaryStage; 
    ... 
} 

public void changeScene(String fxml){ 
    Parent pane = FXMLLoader.load(
      getClass().getResource(fxml)); 

    Scene scene = new Scene(pane); 
    primaryStage.setScene(scene); 
}

然而，由于已经指出的@Eugene_Ryzhikov这是一个更好的解决方案只是改变现有场景的根内容：

public void changeScene(String fxml){ 
    Parent pane = FXMLLoader.load(
      getClass().getResource(fxml)); 

    primaryStage.getScene().setRoot(pane); 
}

我试过这个，但我不断得到一个空指针异常。在收到关于同一件事的两条评论后，我决定发布我的异常消息，参见上文。 – Megan

你在哪里得到'NullPointerException'的代码是什么？ – hotzst

上面我添加了我得到的异常，底部有笔记。但是我在没有使用Scene Builder的情况下累了几个类似的例子，并且它的工作非常好，所以它肯定与Scene Builder有关 – Megan

答

看来OP已经解决了它，但由于它仍然是开放和未解决的，我会分享我在另一个答案中找到的解决方案。记住要么选择正确的答案，要么在问题解决后发布自己的解决方案，它有助于未来的人们在同一问题中运行（就像我一样）。

我只是运行在同一个问题和this answer完美解决了我的问题，同时又短又干净。

@FXML 
private void handleButtonAction(ActionEvent event) { 
System.out.println("You clicked me!"); 
label.setText("Hello World!"); 
//Here I want to swap the screen! 

Stage stageTheEventSourceNodeBelongs = (Stage) ((Node)event.getSource()).getScene().getWindow(); 
// OR 
Stage stageTheLabelBelongs = (Stage) label.getScene().getWindow(); 
// these two of them return the same stage 
// Swap screen 
stage.setScene(new Scene(new Pane())); 

}

PS .:记得检查原来的答案，并upvote它。这家伙值得...

PPS .:我不知道只是复制一个答案是好的（而不是只是通过评论分享链接），但因为这没有一个正确的答案，但我决定做它的可见性。

答

TypesController.java 
package todoapp; 
import java.io.IOException; 
import java.net.URL; 
import java.util.ResourceBundle; 
import javafx.event.ActionEvent; 
import javafx.fxml.FXML; 
import javafx.fxml.FXMLLoader; 
import javafx.fxml.Initializable; 
import javafx.scene.Node; 
import javafx.scene.Parent; 
import javafx.scene.Scene; 
import javafx.scene.control.CheckBox; 
import javafx.stage.Stage; 

public class TypesController implements Initializable { 
@FXML 
private CheckBox c1; 
@FXML 
private CheckBox c2; 
public void clicked(ActionEvent e) throws IOException { 
Parent home_page_parent =FXMLLoader.load(getClass().getResource("AddDcuFXML.fxml")); 
Scene home_page_scene = new Scene(home_page_parent); 
Stage app_stage = (Stage) ((Node) e.getSource()).getScene().getWindow(); 
app_stage.hide(); //optional 
app_stage.setScene(home_page_scene); 
app_stage.show(); 
} 
public void clicked1(ActionEvent e) throws IOException { 
Parent home_page_parent = FXMLLoader.load(getClass().getResource("AddDcuFXML.fxml")); 
    Scene home_page_scene = new Scene(home_page_parent); 
    Stage app_stage = (Stage) ((Node)e.getSource()).getScene().getWindow(); 
    app_stage.hide(); //optional 
    app_stage.setScene(home_page_scene); 
    app_stage.show(); 
    } 
    @Override 
    public void initialize(URL arg0, ResourceBundle arg1) { 
// TODO Auto-generated method stub 
    } }

对于这样长的代码示例，一些解释会很酷。 – ChristianM

答

<?xml version="1.0" encoding="UTF-8"?> 
<?import javafx.scene.image.*?> 
<?import javafx.scene.text.*?> 
<?import java.lang.*?> 
<?import java.util.*?> 
<?import javafx.scene.*?> 
<?import javafx.scene.control.*?> 
<?import javafx.scene.layout.*?> 
<AnchorPane id="AnchorPane" prefHeight="491.0" prefWidth="386.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="todoapp.TypesController"> 
<children> 
    <CheckBox fx:id="c1" layoutX="55.0" layoutY="125.0" mnemonicParsing="false" onAction="#clicked" text="ADD dcu" /> 
    <CheckBox fx:id="c2" layoutX="55.0" layoutY="177.0" mnemonicParsing="false" onAction="#clicked1" text="Display dcu" /> 
    <Label layoutX="31.0" layoutY="58.0" prefHeight="37.0" prefWidth="276.0" text="Choose any one of the options" textFill="#1b29cd"> 
    <font> 
     <Font name="Arial Bold" size="18.0" /> 
    </font> 
    </Label> 
</children>

请编辑你的第一个答案，并添加其他答案的片段（加上解释如何/为什么他们解决问题，如评论中所建议的） – kleopatra

只是你知道我发布这个像2年前。我想我所做的只是从答案中收集建议，在Google上进行更多搜索，然后提出答案。我对编程还很陌生，不知道自己在做什么 – Megan

如何在JavaFX中切换场景

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