为什么 Parent root =FXMLLoader 不能正常工作？

Question

我正在尝试使用 JavaFX 构建应用程序，但我遇到了这个问题。自从我创建项目以来，下面的代码生成 error.I 错误。我从“https://gluonhq.com/products/javafx/”下载了 JavaFX 14，并将所有 jar 文件包含在 lib 目录中。


import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception{
        Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
        primaryStage.setTitle("Hello World");
        primaryStage.setScene(new Scene(root));
        primaryStage.show();
    }


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

但是这段代码工作正常

package sample;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception{
        //Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
        StackPane root=new StackPane();
        primaryStage.setTitle("Hello World");
        primaryStage.setScene(new Scene(root));
        primaryStage.show();
    }


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

出现此错误：

"C:\Program Files\Java\jdk-14.0.1\bin\java.exe" --add-modules javafx.base,javafx.graphics --add-reads javafx.base=ALL-UNNAMED --add-reads javafx.graphics=ALL-UNNAMED "-javaagent:C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2020.1.3\lib\idea_rt.jar=60984:C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2020.1.3\bin" -Dfile.encoding=UTF-8 -classpath E:\Shapes\out\production\Shapes;E:\Software\javafx-sdk-14.0.2.1\lib\javafx-swt.jar;E:\Software\javafx-sdk-14.0.2.1\lib\javafx.base.jar;E:\Software\javafx-sdk-14.0.2.1\lib\javafx.controls.jar;E:\Software\javafx-sdk-14.0.2.1\lib\javafx.fxml.jar;E:\Software\javafx-sdk-14.0.2.1\lib\javafx.graphics.jar;E:\Software\javafx-sdk-14.0.2.1\lib\javafx.media.jar;E:\Software\javafx-sdk-14.0.2.1\lib\javafx.swing.jar;E:\Software\javafx-sdk-14.0.2.1\lib\javafx.web.jar -p E:\Software\javafx-sdk-14.0.2.1\lib\javafx.base.jar;E:\Software\javafx-sdk-14.0.2.1\lib\javafx.graphics.jar sample.Main
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:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:464)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:363)
    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:564)
    at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1051)
Caused by: java.lang.RuntimeException: Exception in Application start method
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:900)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication(LauncherImpl.java:195)
    at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: java.lang.IllegalAccessError: class com.sun.javafx.fxml.FXMLLoaderHelper (in unnamed module @0x66dac2b5) cannot access class com.sun.javafx.util.Utils (in module javafx.graphics) because module javafx.graphics does not export com.sun.javafx.util to unnamed module @0x66dac2b5
    at com.sun.javafx.fxml.FXMLLoaderHelper.<clinit>(FXMLLoaderHelper.java:38)
    at javafx.fxml.FXMLLoader.<clinit>(FXMLLoader.java:2056)
    at sample.Main.start(Main.java:14)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1(LauncherImpl.java:846)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait(PlatformImpl.java:455)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater(PlatformImpl.java:428)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater(PlatformImpl.java:427)
    at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop(WinApplication.java:174)
    ... 1 more
Exception running application sample.Main

Process finished with exit code 1

Answer 1

基本错误是（为了便于阅读而格式化）：

Caused by: java.lang.IllegalAccessError: 
    class com.sun.javafx.fxml.FXMLLoaderHelper (in unnamed module @0x66dac2b5) 
    cannot access class com.sun.javafx.util.Utils (in module javafx.graphics) 
    because module javafx.graphics does not export com.sun.javafx.util to unnamed module @0x66dac2b5

该错误告诉您 javafx.fxml 模块在 class-path 上结束，而 javafx.graphics 模块在 module-path 上。这种情况阻止了 javafx.graphics 模块授予 javafx.fxml 模块对内部代码的特殊访问权限。

解决此问题的方法是执行以下操作之一：

在您的 --add-modules VM 参数中包含 javafx.fxml。
使您自己的代码模块化，添加必要的 requires、exports 和 opens指令，然后使用 --module.

如果您对上述错误是如何产生的感到好奇，那么会详细介绍。请注意，它侧重于 javafx.media 模块，但概念是相同的。

为什么 Parent root =FXMLLoader 不能正常工作？

Why Parent root =FXMLLoader is not working properly?

java

javafx