加载FXML时解析"onAction"出错

23
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:

I'm having some issues getting a simple hello world application to run. It is throwing the following error:


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printHelloprintWorld方法,我希望在按下它们对应的按钮时调用它们。代码如下:

package sample;
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。它们的代码如下:

<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?

先提前道歉,格式很糟糕,这是我第一次发布。


请发布您正在尝试运行的实际代码。 - mjuarez
这应该可以工作。您能否确保在fxml中提供了正确的控制器类名称?或者,将完整的fxml以及Controller的包名称发布在此处。 - ItachiUchiha
1个回答

74

在控制器类中,您导入了错误的 ActionEvent

import java.awt.event.ActionEvent;

将其纠正为

import javafx.event.ActionEvent;

如果我已经正确导入了内容,但问题仍然存在,您有什么建议? - Riley Fitzpatrick
这解决了我的问题。Netbeans 导入了错误的 ActionEvent 类。 - Javier Reséndiz
@RileyFitzpatrick 我建议检查控制器中是否存在该方法。 - yamanidev

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