在将按钮添加到布局时获取java.lang.reflect.InvocationTargetException [英] getting java.lang.reflect.InvocationTargetException while adding a button to layout

问题描述

我在javafx中是全新的！！ 我尝试了一个非常非常简单的代码，但被卡住了. 当我尝试将按钮添加到布局时，它不起作用. 我知道这个问题可能太简单了，但我真的不知道如何解决. 如果您能帮助我，我将不胜感激. 这是我的代码:

I am totally new in javafx!! I tried a very very simple code and I got stuck. when I tried to add a button to the layout It does not work. I know this question may be too simple but I really do not know how to fix it. I would appreciated if you could help me. This is my code:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;


public class Test extends Application{

    Button button;

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

    @Override
    public void start(Stage stage) throws Exception {
        stage.setTitle("Title");
        StackPane layout = new StackPane();

        button = new Button();
        layout.getChildren().add(button);
        Scene scene = new Scene(layout);
        stage.setScene(scene);
        stage.show();
    }
}

我得到了错误:

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:566)
    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:566)
    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$2(LauncherImpl.java:195)
    at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.IllegalAccessError: superclass access check failed: class com.sun.javafx.scene.control.ControlHelper (in unnamed module @0x46b3f4cf) cannot access class com.sun.javafx.scene.layout.RegionHelper (in module javafx.graphics) because module javafx.graphics does not export com.sun.javafx.scene.layout to unnamed module @0x46b3f4cf
    at java.base/java.lang.ClassLoader.defineClass1(Native Method)
    at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
    at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174)
    at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:802)
    at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:700)
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:623)
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
    at javafx.scene.control.Control.<clinit>(Control.java:86)
    at Test.start(Test.java:21)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:846)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:455)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:428)
    at java.base/java.security.AccessController.doPrivileged(Native Method)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:427)
    at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$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$3(WinApplication.java:174)
    ... 1 more
Exception running application Test

推荐答案

从错误中我假设您正在使用JavaFX 11(或至少是JavaFX 9+).请注意，最终问题不是> ，而是IllegalAccessError:

From the error I'm assuming you're using JavaFX 11 (or at least JavaFX 9+). Note that the ultimate problem is not the InvocationTargetException but the IllegalAccessError:

Caused by: java.lang.IllegalAccessError: superclass access check failed: class com.sun.javafx.scene.control.ControlHelper (in unnamed module @0x46b3f4cf) cannot access class com.sun.javafx.scene.layout.RegionHelper (in module javafx.graphics) because module javafx.graphics does not export com.sun.javafx.scene.layout to unnamed module @0x46b3f4cf

这是告诉您未命名模块"中的代码正在尝试访问javafx.graphics模块的内部.由于不允许这样做，因此会引发错误.但是这里真正的问题是ControlHelper在未命名的模块中，但是应该在javafx.controls模块中，前提是要使用软件包名称.此问题是由于在 modulepath 上具有javafx.graphics而在 classpath 上具有javafx.controls引起的.

This is telling you code in the "unnamed module" is trying to access internals of the javafx.graphics module. As this is not allowed the error is thrown. But the real problem here is that ControlHelper is in the unnamed module but it's supposed to be in the javafx.controls module, if the package name is anything to go by. This problem is caused by having javafx.graphics on the modulepath but javafx.controls on the classpath.

确保在--module-path上同时具有两个模块(和javafx.base).由于您的代码不是模块化的(没有module-info文件)，因此您还必须告诉模块系统使用以下方法来解决该问题:

Make sure you have both modules (and javafx.base) on the --module-path. As your code is not modular (no module-info file) you will also have to tell the module system to resolve it by using:

--add-modules javafx.controls

您不必在--add-modules命令中包含javafx.graphics，因为javafx.controls需要javafx.graphics(而javafx.graphics需要javafx.base).由于所有模块都位于模块路径上，因此它们将得到解决.

You don't have to include javafx.graphics in the --add-modules command because javafx.controls requires javafx.graphics (and javafx.graphics requires javafx.base). As all modules are on the modulepath they will be resolved.

如何设置这些命令取决于启动应用程序的方式(例如，命令行，IDE，Maven，Gradle等).

How you set these commands is dependent on how you launch your application (e.g. command-line, IDE, Maven, Gradle, etc...).

如果您曾经使代码模块化，则不需要使用--add-modules命令，只需将相应的requires指令放入您的module-info文件中.例如:

If you ever make your code modular you won't need to use the --add-modules command, just put the appropriate requires directives in your module-info file. For example:

module app {
    requires javafx.controls;
}

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