为什么FXMLLoader在加载FXML文件时给出错误?

Question

我遵循JavaFX教程并编写了以下代码。

所有必需的头文件都已导入。

Main.java

public class Main extends Application {
@Override
public void start(Stage primaryStage){
try {
Parent root = FXMLLoader.load(getClass().getResource("Main.fxml"));

Scene scene = new Scene(root);
scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
primaryStage.setScene(scene);
primaryStage.setTitle("Random Number Generator");
primaryStage.show();
}catch(Exception e) {
e.printStackTrace();
}

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

主要。fxml(使用SceneBuilder创建)

<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane minHeight="100.0" minWidth="100.0" prefHeight="300.0" prefWidth="500.0" xmlns="http://javafx.com/javafx/8.0.171" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.MainController">
<children>
<Button id="button_generateRandomNumber" layoutX="171.0" layoutY="212.0" mnemonicParsing="false" onAction="#generateRandom" text="Generate Random Number" textAlignment="CENTER" textFill="#1e4d0e" />
<Label fx:id="message" layoutX="112.0" layoutY="143.0" prefHeight="45.0" prefWidth="258.0" textAlignment="CENTER" />
</children>
</AnchorPane>

异常堆栈

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$2(LauncherImpl.java:195)
at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: java.lang.IllegalAccessError: class com.sun.javafx.fxml.FXMLLoaderHelper (in unnamed module @0x5d85fddd) cannot access class com.sun.javafx.util.Utils (in module javafx.graphics) because module javafx.graphics does not export com.sun.javafx.util to unnamed module @0x5d85fddd
at com.sun.javafx.fxml.FXMLLoaderHelper.<clinit>(FXMLLoaderHelper.java:38)
at javafx.fxml.FXMLLoader.<clinit>(FXMLLoader.java:2056)
at application.Main.start(Main.java:20)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$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$10(PlatformImpl.java:428)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$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 application.Main

我已经尝试了getResource("Main.fxml")的所有组合，包括相对和绝对路径，以各种可能的方式，我仍然得到错误。代码与该教程100%相同。

Answer 1

为了javafx工作，您需要下载并导入javafx sdk到您的项目中，或者指定依赖，如果您正在使用构建工具，如Maven或Gradle。

此外>您需要添加所需的模块(在本例中是javafx的.jars)，方法是使用module-info.java并在那里指定所需的模块，或者将模块添加到VM参数

- https://openjfx.io/openjfx-docs/#install-javafx. 。奖励:注意javafx在JDK版本10中存在javafx。自版本11他们把它移走了。这就是为什么您需要以某种方式将javafx导入到您的项目中。