Agfdhyk

Hello i have problem with handling action from my button: here's my code:

public class HelloWorld extends Application {

Button btn;

@Override

public void start(Stage primaryStage) {

    btn = new Button();

    btn.setText("Say 'Hello World'");





    StackPane root = new StackPane();

    root.getChildren().add(btn);



    Scene scene = new Scene(root, 300, 250);



    primaryStage.setTitle("Hello World!");

    primaryStage.setScene(scene);

    primaryStage.show();

} 

public void setButtonOnAction(EventHandler<ActionEvent> acn)

{

   btn.setOnAction(acn);

 }



  }

my controller class

 public class Controller  {

private  HelloWorld helloWorld;

private  Model model;







public Controller(HelloWorld helloWorld, Model model) throws Exception {

    this.helloWorld = helloWorld;

    this.model = model;



    System.out.println(this.mainView.returnOne());

    this.helloWorld.setButtonOnAction(e->

    {

        System.out.println("CATCH");

            });

}

 }

main runClass:

  public class runExample {











public static void main(String args) throws Exception {

    HelloWorld helloWorld = new HelloWorld();

    Model model = new Model();







    Application.launch(helloWorld.getClass(),args);







    Controller controller = new Controller(helloWorld, model);

 }



 }

`

Does anyone know why setButtonOnAction don't work in controller class but in HelloWorld class it work perfectly ? Compiler don't give me any error. Only if i switch in run class like that:

Controller controller = new Controller(mainView, model);

    Application.launch(mainView.getClass(),args); 

it gives me

Exception in thread "main" java.lang.NullPointerException

and if i'm using setButtonOnAction in HelloWorld class it works fine. Can u help me catch event in my controller class ? I'm using jdk8 but on 11 it isn't work too.

Working example ;)

public class HelloWorld extends Application {

Button btn;

@Override

public void start(Stage primaryStage) {

btn = new Button();

btn.setText("Say 'Hello World'");





StackPane root = new StackPane();

root.getChildren().add(btn);



Scene scene = new Scene(root, 300, 250);

Controller controller = new Controller(this,new Model()));

primaryStage.setTitle("Hello World!");

primaryStage.setScene(scene);

primaryStage.show();

 } 

 public void setButtonOnAction(EventHandler<ActionEvent> acn)

{

 btn.setOnAction(acn);

 }



 }

And run class:

  public class runExample {



          public static void main(String args) throws Exception {

           Application.launch(HelloWorld.class,args);

          }



                  }