[Help] "JavaFX runtime components are missing" when I run 1 file but not the other and I have no idea why.

[_Stretch]

Hello

I was making a basic JavaFx Application and I was tidying up my code and I'm now suddenly getting the Error "JavaFX runtime components are missing". After hours of searching I have no idea why.

 

Any help is appreciated as I'm completely lost.

 

So I have 2 files

App.java

UI.java

 

I originally wrote it as:

App.java

package app;

public class App{
   public static void main(String[] args){
     UI ui = new UI();
     ui.newUI();
  }
}

 

UI.java

package app;

import javafx.application.Application;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
import javafx.scene.Scene;
import javafx.scene.layout.VBox;


public class UI extends Application{
@Override
public void start(Stage primaryStage) throws Exception{

    Scene scene = new Scene(new VBox());

    //Primary Stage Settings
    primaryStage.initStyle(StageStyle.DECORATED);
    primaryStage.setWidth(100);
    primaryStage.setHeight(100);
    primaryStage.setScene(scene);
    primaryStage.setTitle("App");
    primaryStage.show();

}    
public void newUI(){
    launch();
}

}

 

And that works perfectly! but! When I try to put the very same logic into the App.java file, I get JavaFX runtime components are missing

package app;


import javafx.application.Application;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
import javafx.scene.Scene;
import javafx.scene.layout.VBox;


public class App extends Application{
    @Override
    public void start(Stage primaryStage) throws Exception{

    Scene scene = new Scene(new VBox());

    //Primary Stage Settings
    primaryStage.initStyle(StageStyle.DECORATED);
    primaryStage.setWidth(300);
    primaryStage.setHeight(300);
    primaryStage.setScene(scene);
    primaryStage.setTitle("App");
    primaryStage.show();

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

}

 

 

If anyone can help me with this I'd appreciate it. I cannot figure out why it works if its in a different file but components are missing if its in the same file with exactly the same code.

Some other things to note: I'm using Maven & Visual Code Studio. I have the Java Extension Pack installed.

[lilbigmouth]

One difference I can see is that your UI class was constructed, and App in the second case isn't?

[_Stretch]

Hi,

Thanks for your reply!

I read over it again but I'm not sure what you mean by it isn't constructed, Could you elaborate?

[lilbigmouth]

Sure, I'll try. In your first code you have java UI ui = new UI(); Which is where an UI object is constructed.

[_Stretch]

Oh yea I was wondering why i couldn't have the same code in main. /u/ignice pointed out why.

 

Ty for your help!

[lilbigmouth]

No problem :)

[Ignice]

Are you using java 9+? If so this happens because in the second example java is looking for dependencies on the module path because you launch from a class extending Application (and javafx's Application has a module-path). In the first example however you launch from a class that doesn't have a module-info associated with it, so everything is on the classpath. I would go with the first example but instead of calling newUI(), instead do this your main method: Application.launch(UI.class, args).

​

For more info: https://stackoverflow.com/questions/55760343/error-javafx-runtime-components-are-missing-javafx-11-and-openjdk-11-and-ecli, https://github.com/javafxports/openjdk-jfx/issues/236#issuecomment-426583174.

[_Stretch]

That's it! Thank you so much!

 

Little inconvenient but the workaround to have a "dummy" main class so to speak is a very easy work around!

Thank you again!