Eclipse 2024-03中JavaFX报Exception in Application start method错误求助

问题概述 #

作为JavaFX新手，尝试多种方案并升级至Eclipse 2024-03（4.31.0）后，仍反复遇到FXML加载错误。已确认FXML文件路径正确，但启动程序时抛出GridPane is not a valid type异常。

代码展示 #

Main.java #

package application;

import javafx.application.*;
import javafx.stage.*;
import javafx.scene.*;
import javafx.fxml.*;

public class Main extends Application {
    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage stage) throws Exception {
        FXMLLoader loader = new FXMLLoader(Main.class.getResource("/Test.fxml"));
        if (loader.getLocation() == null) {
            System.out.println("Failed to load FXML");
            return;
        }
        Parent root = loader.load();
        stage.setScene(new Scene(root));
        stage.setTitle("Account");
        stage.sizeToScene();
        stage.show();
    }
}

Test.fxml（原错误版本） #

<?xml version="1.0" encoding="UTF-8"?>

<?import java.net.*?>
<?import javafx.geometry.*?>
<?import java.scene.control.*?>
<?import java.scene.layout.*?>
<?import java.scene.text.*?>

<GridPane xmlns:fx="http://javafx.com/fxml/1">
    alignement="center" hgap="10" vgap="10"
    >

    <Label text="Name:" GridPane.columnIndex="0" GridPane.rowIndex="1"/>
    <TextFiels GridPane.columnIndex="1" GridPane.rowIndex="1"/>
    <Label text="Balance" GridPane.columnIndex="0" GridPane.rowIndex="2"/>
    <TextFiels GridPane.columnIndex="1" GridPane.rowIndex="2"/>

</GridPane>

错误信息 #

Exception in Application start method
java.lang.reflect.InvocationTargetException
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:568)
    at javafx.graphics@21.0.3/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:464)
    at javafx.graphics@21.0.3/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:364)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:568)
    at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1085)
Caused by: java.lang.RuntimeException: Exception in Application start method
    at javafx.graphics@21.0.3/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:893)
    at javafx.graphics@21.0.3/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:196)
    at java.base/java.lang.Thread.run(Thread.java:840)
Caused by: javafx.fxml.LoadException: GridPane is not a valid type.
/C:/Users/edgar/eclipse-workspace-2024/BankAccount/bin/Test.fxml

    at javafx.fxml@21.0.3/javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2718)
    at javafx.fxml@21.0.3/javafx.fxml.FXMLLoader.createElement(FXMLLoader.java:2920)
    at javafx.fxml@21.0.3/javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2850)
    at javafx.fxml@21.0.3/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2649)
    at javafx.fxml@21.0.3/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2563)
    at javafx.fxml@21.0.3/javafx.fxml.FXMLLoader.load(FXMLLoader.java:2531)
    at application.Main.start(Main.java:20)
    at javafx.graphics@21.0.3/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:839)
    at javafx.graphics@21.0.3/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:483)
    at javafx.graphics@21.0.3/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:456)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
    at javafx.graphics@21.0.3/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:455)
    at javafx.graphics@21.0.3/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at javafx.graphics@21.0.3/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at javafx.graphics@21.0.3/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:185)
    ... 1 more
Exception running application application.Main

解决步骤 #

• 修正GridPane的导入路径：FXML中错误导入了java.scene.layout.*，但GridPane属于JavaFX的javafx.scene.layout包，需将导入语句改为：

  <?import javafx.scene.layout.*?>
  

• 修正GridPane标签语法与拼写：将属性移至起始标签内部，同时修正alignement的拼写错误为alignment，正确的GridPane标签写法：

  <GridPane xmlns:fx="http://javafx.com/fxml/1" alignment="center" hgap="10" vgap="10">
  

• 修正文本框组件拼写：将TextFiels改为正确的TextField（缺失字母d）。

修正后的Test.fxml #

<?xml version="1.0" encoding="UTF-8"?>

<?import java.net.*?>
<?import javafx.geometry.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.text.*?>

<GridPane xmlns:fx="http://javafx.com/fxml/1" alignment="center" hgap="10" vgap="10">
    <Label text="Name:" GridPane.columnIndex="0" GridPane.rowIndex="1"/>
    <TextField GridPane.columnIndex="1" GridPane.rowIndex="1"/>
    <Label text="Balance" GridPane.columnIndex="0" GridPane.rowIndex="2"/>
    <TextField GridPane.columnIndex="1" GridPane.rowIndex="2"/>
</GridPane>

内容的提问来源于stack exchange，提问作者Edgar Chauve