Loading fxml file in main

Question

i did this tutorial from youtube, and i have the same code than the tutorial but i did my proper fxml with Scenebuilder. Here is the code: https://github.com/AlmasB/FXTutorials/tree/master/src/com/almasb/calc I have the same Main, same Controller and same Model.. When i try to compile it says to me :

`Exception in Application start method
java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(Unknown Source)
    at com.sun.javafx.application.LauncherImpl.launchApplication(Unknown Source)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at sun.launcher.LauncherHelper$FXHelper.main(Unknown Source)
Caused by: java.lang.RuntimeException: Exception in Application start method
    at com.sun.javafx.application.LauncherImpl.launchApplication1(Unknown Source)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$147(Unknown Source)
    at com.sun.javafx.application.LauncherImpl$$Lambda$48/1394438858.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException: Location is required.
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.loadImpl(Unknown Source)
    at javafx.fxml.FXMLLoader.load(Unknown Source)
    at application.Main.start(Main.java:12)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$153(Unknown Source)
    at com.sun.javafx.application.LauncherImpl$$Lambda$51/1252716230.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$166(Unknown Source)
    at com.sun.javafx.application.PlatformImpl$$Lambda$45/1775282465.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$null$164(Unknown Source)
    at com.sun.javafx.application.PlatformImpl$$Lambda$47/21202996.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$165(Unknown Source)
    at com.sun.javafx.application.PlatformImpl$$Lambda$46/2040495657.run(Unknown Source)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(Unknown Source)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$141(Unknown Source)
    at com.sun.glass.ui.win.WinApplication$$Lambda$37/1558600329.run(Unknown Source)
    ... 1 more
Exception running application application.Main

package application;

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

This is my main :

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

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) {
       try {
        FXMLLoader loader = new FXMLLoader(getClass().getResource("view/Calculatorview.fxml"));
  //    Parent root = FXMLLoader.load(getClass().getResource("view/Calculatorview.fxml"));
        AnchorPane root = (AnchorPane) loader.load();
        Scene scene = new Scene(root);

        primaryStage.setScene(scene);
        primaryStage.show();
    } 
       catch(Exception e)    {
        e.printStackTrace();
    }
    }
    public static void main(String[] args) {
      launch(args);
    }
}

This is my fxml file :

New Main : file structure

Raf · Accepted Answer

Alright. I tried to setup my environment with Java 1.8 and tried the tutorial from the provided link. Here is what I did.

Installed Elcipse Kepler (Java EE)
Followed instructions here for e(fx)clipse https://www.eclipse.org/efxclipse/install.html
Installed all the libs/jars as shown below

After above, I create a new Java project in the eclipse. I right clicked on the project and created two Source Folders namely

src/main/java 
src/main/resources

Then I right clicked on the src/main/java and created new package and named it application. Under application I created 4 java classes and copied across the content from the tutorial link. I did modify the package on top of each java file to reflect the application only.

Here are the java classes

package application;

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

public class App extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception {
        Parent root = FXMLLoader.load(getClass().getResource("/ui.fxml"));

        primaryStage.setScene(new Scene(root));
        primaryStage.show();
    }

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

Controller

 package application;

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.text.Text;

public class Controller {

    @FXML
    private Text output;

    private long number1 = 0;
    private String operator = "";
    private boolean start = true;

    private Model model = new Model();

    @FXML
    private void processNumpad(ActionEvent event) {
        if (start) {
            output.setText("");
            start = false;
        }

        String value = ((Button)event.getSource()).getText();
        output.setText(output.getText() + value);
    }

    @FXML
    private void processOperator(ActionEvent event) {
        String value = ((Button)event.getSource()).getText();

        if (!"=".equals(value)) {
            if (!operator.isEmpty())
                return;

            operator = value;
            number1 = Long.parseLong(output.getText());
            output.setText("");
        }
        else {
            if (operator.isEmpty())
                return;

            output.setText(String.valueOf(model.calculate(number1, Long.parseLong(output.getText()), operator)));
            operator = "";
            start = true;
        }
    }
}

Model

package application;

public class Model {

    public long calculate(long number1, long number2, String operator) {
        switch (operator) {
            case "+":
                return number1 + number2;
            case "-":
                return number1 - number2;
            case "*":
                return number1 * number2;
            case "/":
                if (number2 == 0)
                    return 0;

                return number1 / number2;
        }

        System.out.println("Unknown operator - " + operator);
        return 0;
    }
}

and ui.fxml

I had issues with Java source library (reference to JRE) and the jfxrt.jar files. So I did the following

Removed the referenced library
Removed the external jar that was referenced
Right clicked on the project and choose Properties
Choose Java Build Path
Clicked on Add Library on the right side of the window and added JRE System Library as shown below
Added external jar jfxrt.jar

After adding the above, the code was resolved and there were no issues.

Remember, I placed ui.fxml under src/main/resources folder. So when I run the project as Java Application initially, it complained and give me the same exception as you are facing. So I changed the "ui.fxml" to "/ui.fxml" and boom, I saw the calculator.

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

See below the screenshot, I hope these steps help.

Loading fxml file in main

Answers (2)

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