失败@应用程序启动方法（JavaFX 11、JDK 14 和 Intellij）

Question

I'll try to keep this short but include as many details as I can, basically i'm trying to create a simple MPG calculator using Javafx but I've ran into a snag, whenever I attempt to run the main file some errors appear regarding the FXMLLoader but I cant for the life of me figure out why, I researched as many Q&A's as I could (and there is a lot of them) and I tried implementing the answers given but none of them worked.

Im pretty sure this is the cause of my pain.

Parent root = FXMLLoader.load(getClass().getResource("/sample/sample.fxml"));

I am pretty much a newbie when it comes to javafx so any assistance would be appreciated, if more information is required I will provide it.

File Structure

File Structure

Main

package sample;

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 {

    @Override
    public void start(Stage primaryStage) throws Exception{
        Parent root = FXMLLoader.load(getClass().getResource("/sample/sample.fxml"));
        primaryStage.setScene(new Scene(root, 300, 275));
        primaryStage.show();
    }


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

sample.FXML

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

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.ColumnConstraints?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.layout.RowConstraints?>
<?import javafx.scene.text.Font?>


<GridPane alignment="center" hgap="10" prefHeight="267.0" prefWidth="251.0" vgap="10" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/11.0.1" fx:controller="sample.Controller">
   <columnConstraints>
      <ColumnConstraints />
   </columnConstraints>
   <rowConstraints>
      <RowConstraints />
   </rowConstraints>
   <children>
      <AnchorPane prefHeight="279.0" prefWidth="251.0">
         <children>
            <Label layoutX="12.0" layoutY="14.0" prefHeight="35.0" prefWidth="233.0" text="Miles Per Gallon Calculator" textAlignment="CENTER" underline="true">
               <font>
                  <Font size="19.0" />
               </font>
            </Label>
            <Label layoutX="16.0" layoutY="69.0" prefHeight="27.0" prefWidth="50.0" text="Miles">
               <font>
                  <Font size="18.0" />
               </font>
            </Label>
            <Label layoutX="16.0" layoutY="113.0" prefHeight="27.0" prefWidth="68.0" text="Gallons">
               <font>
                  <Font size="18.0" />
               </font>
            </Label>
            <Button layoutX="27.0" layoutY="151.0" mnemonicParsing="false" onAction="#calculateMPG" prefHeight="42.0" prefWidth="206.0" text="Calculate MPG" />
            <TextField fx:id="milesField" layoutX="84.0" layoutY="70.0" />
            <TextField fx:id="gallonsField" layoutX="84.0" layoutY="114.0" />
            <Label layoutX="16.0" layoutY="204.0" prefHeight="27.0" prefWidth="68.0" text="MPG">
               <font>
                  <Font size="18.0" />
               </font>
            </Label>
            <TextField fx:id="mpgField" layoutX="84.0" layoutY="205.0" />
         </children>
      </AnchorPane>
   </children>
</GridPane>

Controller

package sample;

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.TextField;
import java.text.DecimalFormat;

public class Controller {
    DecimalFormat df = new DecimalFormat("#.###"); double mpg;

    @FXML
    private TextField milesField;

    @FXML
    private TextField gallonsField;

    @FXML
    private TextField mpgField;

    @FXML
    void calculateMPG(ActionEvent event) {
        try {
            double miles = Double.parseDouble(milesField.getText());
            double gallons = Double.parseDouble(gallonsField.getText());
            if(gallons == 0){
                mpgField.setText("Cannot Divide by zero");
            }
            else {
                mpg = miles / gallons;
                mpgField.setText(df.format(mpg));
            }

        } catch (NumberFormatException e){
            mpgField.setText("Please enter real numbers.");
        }
    }
}

Error

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$2(LauncherImpl.java:195)
    at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: java.lang.NoSuchMethodError: 'java.lang.Object sun.reflect.misc.ReflectUtil.newInstance(java.lang.Class)'
    at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:927)
    at javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:971)
    at javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:220)
    at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:744)
    at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2707)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3214)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
    at sample.Main.start(Main.java:13)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$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 sample.Main

Process finished with exit code 1

As a quick side note, I was having issues setting up IntelliJ, for some reason when I imported JDK 14 for non-javafx programming it didnt import in any of the Jar files so I had to manually import those modules, same goes for JavaFX modules, here is the images of those as well, if something appears incorrect please let me know.

JDK1

JDK2

JDK3

Edit: Just did a clean install of IntelliJ, JAvaFX,& JDK14, still got the same issue when I attempted to run the basic JavaFX "hello world" although the errors given are much more descriptive, Ill post the new errors here.

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$2(LauncherImpl.java:195)
    at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: java.lang.IllegalAccessError: class com.sun.javafx.fxml.FXMLLoaderHelper (in unnamed module @0x6af6aa0c) cannot access class com.sun.javafx.util.Utils (in module javafx.graphics) because module javafx.graphics does not export com.sun.javafx.util to unnamed module @0x6af6aa0c
    at com.sun.javafx.fxml.FXMLLoaderHelper.<clinit>(FXMLLoaderHelper.java:38)
    at javafx.fxml.FXMLLoader.<clinit>(FXMLLoader.java:2056)
    at sample.Main.start(Main.java:13)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$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 sample.Main

Process finished with exit code 1

Edit 2: Finally cleaned up the errors, after adding this line (see below) to VM options a single issue appeared. (Yes i put my path)

-p /%EnterPathToJavaFX%/lib --add-modules javafx.controls

Error occurred during initialization of boot layer
java.lang.module.FindException: Module javafx.base not found

Going to do some tinkering with the modules folder and see if i can fix this.

Answer 1

So after working on this for a couple of hours, i got a handle on the VM options (which was something I wasnt aware of when i first started) but i'm pretty sure the issue was caused by the use of forward and backward slashes, in a lot of the answers I read, they used forwards slashes instead of backwards slashes, I didnt realize this until about ten minutes ago, its a little embarrassing but, lesson learned.

Anyways, if youre still having this issue i'll give a basic rundown on what should be done (although there are a ton of good answers out there, just remember to use backslashes, dont be a dumb dumb like me).

Important Note: This implementation is for Windows Systems

1st: Ensure that you have your JDK and JavaFX downloaded, try to keep the folder names simple (like JDK14 or JavaFX14).

2nd: Open a new project and select your "Project SDK", in our case select the JDK you downloaded.

3rd: After creating the project go to File -> Project Structure, then under 'Project Settings' select Libraries, then click the Plus icon to the right of project settings, select Java then navigate to your JavaFX folder and select 'lib'.

4th: If you run the project now, you will get a runtime error, instead go to Run (at the top) then select 'Edit Configurations'. In the 'VM Options:' text field enter:

-p *Your_Drive_Partition*:\*path_to_JFX*\JavaFX\lib --add-modules=javafx.controls,javafx.fxml

And now you're done, welcome to JavaFX.

TL;DR: Forward slashes are for URI's and backslashes are for local (windows) files, do not forget this or end up in the same situation as me, going insane from doing the same thing over and over again expecting a different result.

Have a good day.