JavaFX: Location is not set

Question

When I run my app I've got "Exception in Application start method [WARNING] java.lang.reflect.InvocationTargetException". I try with fxml path but still not working. When use try/catch I've got "Location is not set error".

I've got also "Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.2.1:java (default-cli) on project Test-generator-Maven: An exception occured while executing the Java class. null: InvocationTargetException: Exception in Application start method: Location is required." But I don't know what's wrong can be with my pom.xml

My project structure

Code:

Main

public class Main extends Application {

    @Override
    public void start(Stage stage) throws Exception {

        Parent root = FXMLLoader.load(getClass().getResource("../views/MainWindow.fxml"));
        Scene scene = new Scene(root, 900, 400);
        stage.setTitle("Generator testów");
        stage.setScene(scene);
        stage.show();

    }

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

MainWindow.fxml

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

<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.ComboBox?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.ListView?>
<?import javafx.scene.control.RadioButton?>
<?import javafx.scene.control.Slider?>
<?import javafx.scene.control.TextArea?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.control.ToggleGroup?>
<?import javafx.scene.layout.ColumnConstraints?>
<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.layout.RowConstraints?>


<GridPane prefHeight="414.0" prefWidth="864.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.mateuszm.controllers.MainWindowController">
    <columnConstraints>
        <ColumnConstraints hgrow="SOMETIMES" maxWidth="252.0" minWidth="10.0" prefWidth="252.0" />
        <ColumnConstraints hgrow="SOMETIMES" maxWidth="610.4000122070313" minWidth="10.0" prefWidth="503.20000000000005" />
    </columnConstraints>
    <rowConstraints>
        <RowConstraints minHeight="10.0" vgrow="SOMETIMES" />
    </rowConstraints>

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.mateuszm</groupId>
    <artifactId>Test-generator-Maven</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-controls</artifactId>
            <version>11</version>
        </dependency>

        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-media</artifactId>
            <version>11</version>
            <classifier>win</classifier>
        </dependency>

        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-media</artifactId>
            <version>11</version>
            <classifier>mac</classifier>
        </dependency>

        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-media</artifactId>
            <version>11</version>
            <classifier>linux</classifier>
        </dependency>

        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-graphics</artifactId>
            <version>11</version>
            <classifier>win</classifier>
        </dependency>

        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-graphics</artifactId>
            <version>11</version>
            <classifier>mac</classifier>
        </dependency>

        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-graphics</artifactId>
            <version>11</version>
            <classifier>linux</classifier>
        </dependency>

        <dependency>
            <groupId>org.openjfx</groupId>
            <artifactId>javafx-fxml</artifactId>
            <version>11</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.0</version>
                <configuration>
                    <source>11</source>
                    <target>11</target>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>exec-maven-plugin</artifactId>
                <version>1.2.1</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>java</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <mainClass>com.mateuszm.main.Main</mainClass>
                </configuration>
            </plugin>


        </plugins>
    </build>


</project>

Answer 1

move your fxml on main.java.resources

and use Parent root = FXMLLoader.load(getClass().getResource("MainWindow.fxml"));

Answer 2

I've written a utiltiy class for loading FXML files to reduce errors like these.

If you stick to some naming conventions, you can load a FXML file with:

Parent root = FXMLLoaders.load(Main.class);

It loads the <class name>.fxml file, which is expected to be in the same package as the specified type, and sets:

• the ClassLoader to the ClassLoader of the specified type
• the ResourceBundle by looking for a <name>.properties file in the same package, where <name> is equal to the name of the specified type (or a locale specific derivation using the default Locale)
• the location to the FXML file

The library is Open Source and available from Maven Central :

<dependency>
  <groupId>org.drombler.commons</groupId>
  <artifactId>drombler-commons-fx-core</artifactId>
  <version>0.13</version>
</dependency>