单击按钮后如何打开新的 fxml 视图 - JavaFX

Question

嗨，我在单击按钮后打开新窗口 fxml 视图时遇到问题。主窗口显示，在主视图中我有六个按钮。我想我点击按钮打开新窗口。但是，当我单击按钮时，显示异常：
java.lang.reflect.InvocationTargetException

我尝试在互联网上找到的不同解决方案，但显示此异常。主要是我尝试在我的switch函数中修改代码，负责显示新视图。我认为问题出在这里或主类中的代码。

Main class:
    public class Main extends Application {
         public void start(Stage stage) throws Exception {
           AnchorPane pane =   FXMLLoader.load(getClass().getResource("/mainView.fxml"));
        Scene scene = new Scene(pane);
        stage.setScene(scene);
        stage.show();
    }
    @Override
    public void init() {
        System.out.println("Init");
    }
    @Override
    public void stop() {
        System.out.println("Stop");
    }

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

MainController.java
public class MainController {
    @FXML
    private Button addChangeMainButton;
    @FXML
    private Button viewChangesButton;
    @FXML
    private Button addChangeBoughtButton;
    @FXML
    private Button viewContractsButton;
    @FXML
    private Button addContractButton;
    @FXML
    private Button viewStatisticsButton;


    @FXML
    void chooseViewAction(ActionEvent event) throws IOException {
        Button button = (Button) event.getSource();
        String buttonId = button.getId();
        MainLogic mainl = new MainLogic();
        mainl.chooseView(buttonId);
    }
}

public class MainLogic {
   private String chooseView;

   public void chooseView(String chooseView) throws IOException {
       switch (chooseView) {
           case "addChangeMainButton":
               FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("addChangeVIEW.fxml"));
               Parent root1 = fxmlLoader.load();
               Stage stage = new Stage();
               stage.setScene(new Scene(root1));
               stage.show();
               break;
           case "viewChangesButton":
               System.out.println("viewChangesButton");
               break;
           case "addChangeBoughtButton":
               System.out.println("addChangeBoughtButton");
               break;
           case "viewContractsButton":
               System.out.println("viewContractsButton");
               break;
           case "addContractButton":
               System.out.println("addContractButton");
               break;
           case "viewStatisticsButton":
               System.out.println("viewStatisticsButton");
               break;
               default:
                   System.out.println("default");
                   break;
       }
   }

}

mainView.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/10.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.controller.MainController">
   <children>
      <Button fx:id="addChangeMainButton" layoutX="31.0" layoutY="45.0" mnemonicParsing="false" onAction="#chooseViewAction" prefHeight="70.0" prefWidth="150.0" text="Add Change" />
      <Button fx:id="viewChangesButton" layoutX="31.0" layoutY="283.0" mnemonicParsing="false" onAction="#chooseViewAction" prefHeight="70.0" prefWidth="150.0" text="View Changes" />
      <Button fx:id="addChangeBoughtButton" layoutX="217.0" layoutY="45.0" mnemonicParsing="false" onAction="#chooseViewAction" prefHeight="70.0" prefWidth="150.0" text="Change Bought/Sold" />
      <Button fx:id="viewContractsButton" layoutX="225.0" layoutY="283.0" mnemonicParsing="false" onAction="#chooseViewAction" prefHeight="70.0" prefWidth="150.0" text="View Contracts" />
      <Button fx:id="addContractButton" layoutX="403.0" layoutY="45.0" mnemonicParsing="false" onAction="#chooseViewAction" prefHeight="70.0" prefWidth="150.0" text="Add Contract" />
      <Button fx:id="viewStatisticsButton" layoutX="403.0" layoutY="283.0" mnemonicParsing="false" onAction="#chooseViewAction" prefHeight="70.0" prefWidth="150.0" text="View Statistics" />
   </children>
</AnchorPane>

addChangeVIEW.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.AnchorPane?>

<AnchorPane prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/10.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.controller.addChangeController">
   <children>
      <Button fx:id="button" layoutX="263.0" layoutY="210.0" mnemonicParsing="false" text="Button" />
   </children>
</AnchorPane>

addChangeController.java
package com.controller;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
public class addChangeController {
    @FXML
    private Button button;
}

module-info.java
module ProjectCPApril {
    requires javafx.graphics;
    requires javafx.fxml;
    requires javafx.controls;
    exports com.controller to javafx.graphics;
    opens com.controller to javafx.fxml;
    exports com.logic to javafx.graphics;
    opens com.logic to javafx.fxml;
}

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1787)
    at javafx.fxml/javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1670)
    at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at javafx.base/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
    at javafx.base/javafx.event.Event.fireEvent(Event.java:198)
    at javafx.graphics/javafx.scene.Node.fireEvent(Node.java:8879)
    at javafx.controls/javafx.scene.control.Button.fire(Button.java:200)
    at javafx.controls/com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:206)
    at javafx.controls/com.sun.javafx.scene.control.inputmap.InputMap.handle(InputMap.java:274)
    at javafx.base/com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
    at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
    at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at javafx.base/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.base/javafx.event.Event.fireEvent(Event.java:198)
    at javafx.graphics/javafx.scene.Scene$MouseHandler.process(Scene.java:3851)
    at javafx.graphics/javafx.scene.Scene$MouseHandler.access$1200(Scene.java:3579)
    at javafx.graphics/javafx.scene.Scene.processMouseEvent(Scene.java:1849)
    at javafx.graphics/javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2588)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:397)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
    at java.base/java.security.AccessController.doPrivileged(Native Method)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:434)
    at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:390)
    at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:433)
    at javafx.graphics/com.sun.glass.ui.View.handleMouseEvent(View.java:556)
    at javafx.graphics/com.sun.glass.ui.View.notifyMouse(View.java:942)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
    at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.reflect.InvocationTargetException
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:566)
    at com.sun.javafx.reflect.Trampoline.invoke(MethodUtil.java:76)
    at jdk.internal.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:566)
    at javafx.base/com.sun.javafx.reflect.MethodUtil.invoke(MethodUtil.java:273)
    at javafx.fxml/com.sun.javafx.fxml.MethodHelper.invoke(MethodHelper.java:83)
    at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1782)
    ... 47 more
Caused by: java.lang.IllegalStateException: Location is not set.
    at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2459)
    at javafx.fxml/javafx.fxml.FXMLLoader.load(FXMLLoader.java:2435)
    at ProjectCPApril/com.logic.MainLogic.chooseView(MainLogic.java:27)
    at ProjectCPApril/com.controller.MainController.chooseViewAction(MainController.java:43)
    ... 58 more
Stop
Process finished with exit code 0

Answer 1

将注释中的信息复制到答案中

堆栈跟踪的重要部分是：

Caused by: java.lang.IllegalStateException: Location is not set.
    at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2459)
    at javafx.fxml/javafx.fxml.FXMLLoader.load(FXMLLoader.java:2435)
    at ProjectCPApril/com.logic.MainLogic.chooseView(MainLogic.java:27)
    at ProjectCPApril/com.controller.MainController.chooseViewAction(MainController.java:43)
    ... 58 more

这告诉您，当您呼叫load时，FXMLLoader的位置null。当您通过Class.getResource设置它时，这意味着所述方法返回null。当getResource返回null时，这意味着无法使用给定路径找到资源。

您当前使用 "addChangeVIEW" 作为路径，但您说：

addChangeVIEW.fxml位于文件夹 resources 中，MainLogic.java位于包com.logic

由于您的路径没有引导/因此它与您调用getResource Class有关。由于您使用MainLogic.class因此路径被解析为com/logic/addChangeVIEW.fxml - 这不是您拥有资源的地方。您已将资源放在类路径的根目录中，可以使用绝对路径 "/addChangeVIEW.fxml" 检索该类路径。

有关详细信息，请参阅Class.getResource(String)。