I am facing java.lang.reflect.InvocationOnTargetException - javafx

Question

My Main.java class code. I Have searched the old question and answer and already tried different solution but in vain. Please I have wasted whole day to resolve the issue. Any help please.
package application;
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 {
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage primaryStage) throws Exception {
Parent root = FXMLLoader.load(getClass().getResource("testcode.fxml"));
Scene scene = new Scene(root);
primaryStage.setScene(scene);
primaryStage.show();
}
}
testcode.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane prefHeight="420.0" prefWidth="508.0" xmlns="http://javafx.com/javafx/10.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="MainController.java">
<children>
<Button id="btn1" layoutX="216.0" layoutY="178.0" mnemonicParsing="false" onAction="#generateRandom" text="Test Button" />
</children>
</AnchorPane>
complete stack trace of the exception
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(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.base/java.lang.reflect.Method.invoke(Unknown Source)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(Unknown Source)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(Unknown Source)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.base/java.lang.reflect.Method.invoke(Unknown Source)
at java.base/sun.launcher.LauncherHelper$FXHelper.main(Unknown Source)
Caused by: java.lang.RuntimeException: Exception in Application start method
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(Unknown Source)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(Unknown Source)
at java.base/java.lang.Thread.run(Unknown Source)
Caused by: javafx.fxml.LoadException:
/E:/eclipse/eclipse-workspace/JavaFXDemo/bin/application/testcode.fxml:6
at javafx.fxml/javafx.fxml.FXMLLoader.constructLoadException(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader.access$700(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader$ValueElement.processAttribute(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader$Element.processStartElement(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader$ValueElement.processStartElement(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader.processStartElement(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
at javafx.fxml/javafx.fxml.FXMLLoader.load(Unknown Source)
at application.Main.start(Main.java:19)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(Unknown Source)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$11(Unknown Source)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$9(Unknown Source)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(Unknown Source)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(Unknown Source)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(Unknown Source)
... 1 more
Caused by: java.lang.ClassNotFoundException: MainController.java
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(Unknown Source)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(Unknown Source)
at java.base/java.lang.ClassLoader.loadClass(Unknown Source)
... 23 more
Exception running application application.Main
Adding Class Heirarchy as well of eclipse ide.
enter image description here
Controller code added.
package Controller;
import java.util.Random;
import javafx.event.ActionEvent;
public class MainController {
public void generateRandom(ActionEvent event) {
Random random = new Random();
int rand = random.nextInt(100) + 1;
System.out.println(Integer.toString(rand));
}
}

Answer 1

Your controller class has to be in the same package as the rest of your project for the FXML file to access it.
Moving it to the application package should fix this.
fx:controller= MainController.java In your FXML controller declaration, you are supposed to put the class path so you should change this to fx:controller=application.MainController
The generate random method is called whenever the button is pressed and works with no parameters.