import javafx.application.Application;
import javafx.scene.layout.*;
import javafx.scene.*;
import javafx.scene.control.*;
import javafx.stage.Stage;
import javafx.scene.text.*;
import javafx.scene.shape.Rectangle;
import javafx.scene.paint.*;
import javafx.event.*;

public class HeiVerden extends Application {
    Button knapp = null;

    @Override
    public void start(Stage stage) {
        VBox root = new VBox();
        knapp = new Button("Si hei");
        knapp.setOnAction(new Knappebehandler());
        root.getChildren().add(knapp);

        stage.setScene(new Scene(root, 200, 200));
        stage.show();
    }

    class Knappebehandler implements EventHandler<ActionEvent> {
        @Override
        public void handle(ActionEvent e) {
            knapp.setText("Hei!");
            knapp.setOnAction(new Knappebehandler2());
        }
    }

    class Knappebehandler2 implements EventHandler<ActionEvent> {
        @Override
        public void handle(ActionEvent e) {
            knapp.setText("Surprise!");
            knapp.setOnAction(new Knappebehandler());
        }
    }

}