如何在 JavaFX 中交换控制器？ java.lang.reflect.InvocationTargetException

Question

我已经检查了一些答案，但几个小时后仍然没有得到任何答案，所以我非常绝望。这是我第一次尝试使用场景生成器在 javafx 上使用，我正在创建一个带有菜单和其他几个屏幕的应用程序。我设法正确显示菜单（第一个控制器），但是当涉及到与另一个菜单交换时（在按钮事件之后），应用程序在我面前抛出一个非常长的错误列表，我不知道为什么。

这是错误

 Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1774)
at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Node.fireEvent(Node.java:8413)
at javafx.scene.control.Button.fire(Button.java:185)
at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase.handle(BehaviorSkinBase.java:96)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase.handle(BehaviorSkinBase.java:89)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
at javafx.scene.Scene$MouseHandler.access00(Scene.java:3485)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:381)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent4(GlassViewEventHandler.java:417)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:416)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null8(WinApplication.java:191)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769)
... 48 more
Caused by: javafx.fxml.LoadException: 
/D:/Projekty/PartyAnimal/bin/view/Rules.fxml:14

at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2601)
at javafx.fxml.FXMLLoader.access0(FXMLLoader.java:103)
at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:934)
at javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:971)
at javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:220)
at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:744)
at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2707)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2409)
at controller.MenuController.showRules(MenuController.java:39)
... 58 more
Caused by: java.lang.IllegalAccessException: Class sun.reflect.misc.ReflectUtil can not access a                                                   member of class controller.RulesController with modifiers ""
at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:102)
at java.lang.Class.newInstance(Class.java:436)
at sun.reflect.misc.ReflectUtil.newInstance(ReflectUtil.java:51)
at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:927)
... 66 more

我在主控制器中启动第一个控制器，显示第一个 fxml window，然后我想在单击按钮后切换到第二个 controller/second FXML。我想这不是 fxml 的问题，因为当我在菜单中打开第二个而不是第一个时，一切正常。问题在于切换 fxml 和控制器。我没主意了。

主要：

public class Main extends Application {

@Override
public void start(Stage primaryStage) {
    try {   
        AnchorPane root = (AnchorPane) FXMLLoader.load(Main.class.getResource("../view/Menu.fxml"));
        Scene scene = new Scene(root,1280,720); 
        primaryStage.setTitle("Party Animal");
        primaryStage.setScene(scene);
        primaryStage.show();
    } catch(Exception e) {
        e.printStackTrace();
    }
}

public static void main(String[] args) throws IOException {
    launch(args);
}

}

控制器 1 - 菜单：

package controller;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;

public class MenuController implements Initializable {


String menu_theme;

public MenuController() {
}
@FXML
public void showRules(ActionEvent event) throws IOException {

FXMLLoader loader = new FXMLLoader(getClass().getResource("../view/Rules.fxml"));
     Parent root = loader.load();
     Scene scene = new Scene(root);
     Stage stage = (Stage) ((Node)event.getSource()).getScene().getWindow();
     stage.setTitle("PartyAnimal");
     stage.setScene(scene);
     stage.show();

}}

控制器 2 - 规则：

package controller;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.scene.media.MediaPlayer;
import javafx.stage.Stage;
import javafx.application.Platform;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.media.Media;

public class RulesController {

RulesController() {
System.out.println("blablabababa");
}

}

fxml1 开始 - 菜单：

<AnchorPane prefHeight="720.0" prefWidth="1280.0" styleClass="pane" stylesheets="@Background.css" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="controller.MenuController">
    <children>
<Pane prefHeight="720.0" prefWidth="1280.0" styleClass="pane" stylesheets="@Background.css" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
        <children>
        <Slider id="volumeSlider" layoutX="1147.0" layoutY="681.0" prefHeight="14.0" prefWidth="100.0">
           <effect>

fxml2 的开始 - 规则（第 14 行的错误是这里的第一行，在这些之前只有预制的导入）：

<AnchorPane prefHeight="720.0" prefWidth="1280.0" styleClass="pane" stylesheets="@Background.css" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="controller.RulesController">
   <children>
      <Pane prefHeight="720.0" prefWidth="1280.0" styleClass="pane" stylesheets="@Background.css" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
         <children>
            <Slider id="volumeSlider" layoutX="1147.0" layoutY="681.0" prefHeight="14.0" prefWidth="100.0">
               <effect>

Answer 1

您的 RulesController 需要一个 public 无参数构造函数。

FXMLLoader 将（默认情况下）通过反射调用指定 class 上的无参数构造函数来创建控制器。反射代码假定此构造函数是 public。由于您从构造函数中省略了 public 关键字，因此 FXMLLoader 在尝试创建控制器时失败。

只需更换

RulesController() {
    System.out.println("blablabababa");
}

和

public RulesController() {
    System.out.println("blablabababa");
}

（或完全删除它，因为它什么也没做，默认构造函数是 public 并且具有正确的签名）。

如何在 JavaFX 中交换控制器？ java.lang.reflect.InvocationTargetException

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