import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.layout.VBox;
import javafx.scene.control.Button;
import javafx.event.EventHandler;
import javafx.event.ActionEvent;



public class Hello extends Application {

    Button knapp = null;

    @Override
    public void start (Stage teater) {
        knapp = new Button("Si hei!");
        Knappebehandler behandler = new Knappebehandler();
        knapp.setOnAction(behandler);

        VBox pane = new VBox(knapp);

        teater.setTitle("Velkommen til Java FX");
        teater.setScene(new Scene(pane));
        teater.show();
    }

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

    class Knappebehandler implements EventHandler<ActionEvent> {
        @Override
        public void handle(ActionEvent e) {
            knapp.setText(String.format("Hei verden!"));
        }
    }
}