无法启动javaFX项目中的应用程序

Question

after I added Maven dependecies to my JavaFX program and created a new package, called Algorithm wth two classes, my application fails to start.

Following Exceptions are thrown:

Caused by: java.lang.RuntimeException: Exception in Application start method Caused by: java.lang.NullPointerException: Location is required.

and so on...

I have tried:
JavaFX "Location is required." even though it is in the same package
and
Exception in Application start method java.lang.reflect.InvocationTargetException

Both didn't work

In the image below is my project structure, any help is highly appreciated. It seems that sample.fxml is not valid...

Edit:
relocating the fxml file in resources directory didn't work either

Answer 1

I've just copied this code approximately, put it on my IntelliJ, and it worked like a charm. Maybe you're just missing the / on the name of the resource?

Here's the exact code I used:

package hello;

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

import java.io.IOException;

public class Hello extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception {
        Parent parent = FXMLLoader.load(Hello.class.getResource("/hello.fxml"));
        Scene scene = new Scene(p, 400, 400);
        primaryStage.setTitle("my app");
        primaryStage.setScene(scene);
        primaryStage.centerOnScreen();
        primaryStage.show();
    }

    public static void main(String[] args) throws IOException {
        launch(Hello.class);
    }
}

The FXML file:

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

<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.VBox?>
<?import javafx.scene.text.Text?>
<AnchorPane xmlns="http://javafx.com/javafx"
            xmlns:fx="http://javafx.com/fxml"
            fx:controller="hello.Hello"
            prefHeight="400.0" prefWidth="600.0">
    <VBox>
        <Text>Hello</Text>
    </VBox>
</AnchorPane>

Run with IntelliJ. Works. Create a Jar, run with java -jar... also works.

Answer 2

Your IDE, IntelliJ, loads resources files from the classpath using pattern recognition to match the file extensions. By default, IntelliJ includes extensions like JPG, PNG, HTML, etc...

This means you need to manually specify the file extensions you want to compiler to find, for you that's FXML.

Here are some simple instructions on how to achieve this: https://www.jetbrains.com/help/idea/working-with-projects.html