加载 FXML 时解析“onAction”时出错

Question

我在运行一个简单的 hello world 应用程序时遇到了一些问题。它抛出以下错误：

Exception in Application start method
Exception in thread "main" java.lang.RuntimeException: Exception in Application start method
    at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$152(LauncherImpl.java:182)
    at com.sun.javafx.application.LauncherImpl$$Lambda$2/1329552164.run(Unknown Source)
    at java.lang.Thread.run(Thread.java:745)
Caused by: javafx.fxml.LoadException: Error resolving onAction='#printHello', either the event handler is not in the Namespace or there is an error in the script.
/home/willi/java/IdeaProjects/JavaFXApp/out/production/JavaFXApp/sample/sample.fxml:23

    at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2601)
    at javafx.fxml.FXMLLoader.access$100(FXMLLoader.java:104)
    at javafx.fxml.FXMLLoader$Element.processEventHandlerAttributes(FXMLLoader.java:606)
    at javafx.fxml.FXMLLoader$ValueElement.processEndElement(FXMLLoader.java:766)
    at javafx.fxml.FXMLLoader.processEndElement(FXMLLoader.java:2827)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2536)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2445)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3218)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3179)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3152)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3128)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3108)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3101)
    at sample.Main.start(Main.java:13)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$159(LauncherImpl.java:863)
    at com.sun.javafx.application.LauncherImpl$$Lambda$57/2085742749.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$172(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl$$Lambda$52/738441956.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$null$170(PlatformImpl.java:295)
    at com.sun.javafx.application.PlatformImpl$$Lambda$55/689939224.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$171(PlatformImpl.java:294)
    at com.sun.javafx.application.PlatformImpl$$Lambda$53/1382865734.run(Unknown Source)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
    at com.sun.glass.ui.gtk.GtkApplication.lambda$null$48(GtkApplication.java:139)
    at com.sun.glass.ui.gtk.GtkApplication$$Lambda$43/704249306.run(Unknown Source)
    ... 1 more

我的 Controller.java 文件中定义了 printHello 和 printWorld 方法，我想在按下它们相应的按钮时调用它们。代码如下： 包装样品；

import javafx.fxml.FXML;
import javafx.scene.control.Button;
import java.awt.event.ActionEvent;

public class Controller {

    @FXML
    private Button helloButton;

    @FXML
    private Button worldButton;

    @FXML
    private void printHello(ActionEvent e){
        System.out.println("Hello");
    }

    @FXML
    private void printWorld(ActionEvent f){
        System.out.println("World");
    }
}

` 在我的 fxml 文件中，我定义了两个按钮。他们的代码如下：

<Button fx:id="helloButton" layoutX="46.0" layoutY="87.0" mnemonicParsing="false" onAction="#printHello" text="Hello" />

<Button fx:id="worldButton" layoutX="97.0" layoutY="87.0" mnemonicParsing="false" onAction="#printWorld" text="World" />

为什么我的代码会抛出这个错误？

抱歉，格式很糟糕，这是我第一次发帖。

Answer 1

您在控制器类中导入了错误的ActionEvent。

import java.awt.event.ActionEvent;

改正

import javafx.event.ActionEvent;