应用程序启动方法 JavaFX 1.8 中的异常

Question

I'm having trouble running JavaFX Program which runs on Java version 1.8. I noticed that even if I can run this program on Intellij IDE, it throws

java.lang.reflect.InvocationTargetException

error when I try running it in command line. There are no errors when I use "javac Main.java" but it throws the error after I compile it then type "java Main.java"

Here are the files

src folder

• controller folder

  • Controller.java

• model folder

  • Database.java

• view folder

  • loginview.fxml

  • registerview.fxml

  • mainmenu.fxml

• Main.java

Main.java

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

import model.Database;

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception{
        Parent root = FXMLLoader.load(getClass().getResource("view/mainmenu.fxml"));
        primaryStage.setTitle("Test Program");
        primaryStage.setScene(new Scene(root, 600, 600));
        primaryStage.show();
    }

    public static void main(String[] args) {
        Database db = new Database();
        db.testmethod();

        launch(args);
    }
}

Controller.java

package controller;

import javafx.event.ActionEvent;
import javafx.fxml.FXMLLoader;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

import java.io.IOException;

public class Controller {

    public void exitProgram() {
        System.exit(0);
    }

    public void openRegister(ActionEvent event) {
        Parent root;
        try {
            root = FXMLLoader.load(getClass().getClassLoader().getResource("view/registerview.fxml"));
            javafx.stage.Stage stage = new Stage();
            stage.setTitle("Register User");
            stage.setScene(new Scene(root, 600, 600));
            stage.setResizable(false);
            stage.show();

            close(event);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void openLogin(ActionEvent event) {
        Parent root;
        try {
            root = FXMLLoader.load(getClass().getClassLoader().getResource("view/loginview.fxml"));
            javafx.stage.Stage stage = new Stage();
            stage.setTitle("Login User");
            stage.setScene(new Scene(root, 600, 600));
            stage.setResizable(false);
            stage.show();

            close(event);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void close(ActionEvent event) {
        ((Node) (event.getSource())).getScene().getWindow().hide();
    }
}

Database.java

package model;

public class Database {

    public void testmethod(){
        System.out.println("TEST METHOD");
    }

}

loginview.fxml

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>


<Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="600.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="controller.Controller">
   <children>
      <Label layoutX="134.0" layoutY="145.0" prefHeight="165.0" prefWidth="332.0" text="LOGIN" />
   </children>
</Pane>

mainmenu.fxml

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.Pane?>

<Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="600.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.171" xmlns:fx="http://javafx.com/fxml/1" fx:controller="controller.Controller">
   <children>
      <Button fx:id="buttonReg" layoutX="32.0" layoutY="60.0" mnemonicParsing="false" onAction="#openRegister" prefHeight="104.0" prefWidth="521.0" text="OPEN REGISTER" />
      <Button fx:id="buttonLogin" layoutX="32.0" layoutY="211.0" mnemonicParsing="false" onAction="#openLogin" prefHeight="104.0" prefWidth="521.0" text="OPEN LOGIN" />
      <Button fx:id="buttonExit" layoutX="32.0" layoutY="356.0" mnemonicParsing="false" onAction="#exitProgram" prefHeight="104.0" prefWidth="521.0" text="EXIT" />
   </children>
</Pane>

registerview.fxml

   <?xml version="1.0" encoding="UTF-8"?>

   <?import javafx.scene.control.Label?>
   <?import javafx.scene.layout.Pane?>


   <Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="600.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.171" xmlns:fx="http://javafx.com/fxml/1" fx:controller="controller.Controller">
      <children>
         <Label layoutX="130.0" layoutY="145.0" text="REGISTER" />
      </children>
   </Pane>

The error in command line

TEST METHOD
Exception in Application start method
java.lang.reflect.InvocationTargetException
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
        at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
        at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
        at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$1(LauncherImpl.java:182)
        at java.lang.Thread.run(Thread.java:748)
Caused by: javafx.fxml.LoadException:
/C:/Users/Bryan/Desktop/TESTRUN/src/view/mainmenu.fxml:6

        at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2601)
        at javafx.fxml.FXMLLoader.access$700(FXMLLoader.java:103)
        at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:922)
        at javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:971)
        at javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:220)
        at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:744)
        at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2707)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3214)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
        at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
        at Main.start(Main.java:13)
        at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$8(LauncherImpl.java:863)
        at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$7(PlatformImpl.java:326)
        at com.sun.javafx.application.PlatformImpl.lambda$null$5(PlatformImpl.java:295)
        at java.security.AccessController.doPrivileged(Native Method)
        at com.sun.javafx.application.PlatformImpl.lambda$runLater$6(PlatformImpl.java:294)
        at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
        at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
        at com.sun.glass.ui.win.WinApplication.lambda$null$3(WinApplication.java:177)
        ... 1 more
Caused by: java.lang.ClassNotFoundException: controller.Controller
        at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:352)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
        at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:920)
        ... 22 more
Exception running application Main

I noticed that Database runs before throwing the Error. I don't understand what's the cause of this error

Answer 1

on Main.java,

add

import controller.Controller

Answer 2

Instead of having buttons like "Buttons" try to put them with the class "JFXButton"

You have this:

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.Pane?>

<Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="600.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.171" xmlns:fx="http://javafx.com/fxml/1" fx:controller="controller.Controller">
    <Button fx:id="buttonReg" layoutX="32.0" layoutY="60.0" mnemonicParsing="false" onAction="#openRegister" prefHeight="104.0" prefWidth="521.0" text="OPEN REGISTER" />
    <Button fx:id="buttonLogin" layoutX="32.0" layoutY="211.0" mnemonicParsing="false" onAction="#openLogin" prefHeight="104.0" prefWidth="521.0" text="OPEN LOGIN" />
    <Button fx:id="buttonExit" layoutX="32.0" layoutY="356.0" mnemonicParsing="false" onAction="#exitProgram" prefHeight="104.0" prefWidth="521.0" text="EXIT" />
</Pane>

Try this:

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.Pane?>

<Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="600.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.171" xmlns:fx="http://javafx.com/fxml/1" fx:controller="controller.Controller">
    <JFXButton fx:id="buttonReg" layoutX="32.0" layoutY="60.0" mnemonicParsing="false" onAction="#openRegister" prefHeight="104.0" prefWidth="521.0" text="OPEN REGISTER" />
    <JFXButton fx:id="buttonLogin" layoutX="32.0" layoutY="211.0" mnemonicParsing="false" onAction="#openLogin" prefHeight="104.0" prefWidth="521.0" text="OPEN LOGIN" />
    <JFXButton fx:id="buttonExit" layoutX="32.0" layoutY="356.0" mnemonicParsing="false" onAction="#exitProgram" prefHeight="104.0" prefWidth="521.0" text="EXIT" />
</Pane>

Answer 3

The InvocationTargetException is occurring because the call to method getResource() – in method openRegister() of class Controller – is returning null. You can check this by simply printing out the value returned by method getResource() , for example

System.out.println(getClass().getClassLoader().getResource("view/registerview.fxml"));

It is returning null because method getResource() builds an absolute path to the file registerview.fxml and then checks to see whether such a file exists. The absolute path that method getResources() builds is not the actual path to the file. Hence you need to change the method argument, ie "view/registerview.fxml"

I'm guessing that the below solution is not the only solution, but it worked for me.

In order to prevent getting the InvocationTargetException I did the following.

1. I put class Main in a package which I named jfxtests .
   (It is not clear to me, from your question, whether Main is in a package or not.)
2. I made the controller folder and the view folder sub-packages of jfxtests .
3. I call method getClass().getResource() and not getClass().getClassLoader().getResource() .
4. In class Controller , I changed the argument that I pass to method getResource() .

The only change I made was to class Controller . Here it is with my changes:

package jfxtests.controller;  // changed package

import javafx.event.ActionEvent;
import javafx.fxml.FXMLLoader;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

import java.io.IOException;

public class Controller {

    public void exitProgram() {
        System.exit(0);
    }

    public void openRegister(ActionEvent event) {
        Parent root = null;
        try {
            root = FXMLLoader.load(getClass().getResource("/jfxtests/view/registerview.fxml"));  // changed this line
            javafx.stage.Stage stage = new Stage();
            stage.setTitle("Register User");
            stage.setScene(new Scene(root, 600, 600));
            stage.setResizable(false);
            stage.show();

            close(event);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void openLogin(ActionEvent event) {
        Parent root;
        try {
            root = FXMLLoader.load(getClass().getResource("/jfxtests/view/loginview.fxml"));  // changed this line
            javafx.stage.Stage stage = new Stage();
            stage.setTitle("Login User");
            stage.setScene(new Scene(root, 600, 600));
            stage.setResizable(false);
            stage.show();

            close(event);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void close(ActionEvent event) {
        ((Node) (event.getSource())).getScene().getWindow().hide();
    }
}

Note that since I changed the package for class Controller , I also had to change the FXML files.

fx:controller="jfxtests.controller.Controller"