How to get information from second windows in JavaFXML

I am using the Javafxml program to implement Scotlandyard game. I have a main windows containing the map of London and some control buttons. I need a secondary window that receives number of detectives and other initial information from user. In below code you can see that I set an action for OK button that on click my global variables change. It is good inside the "playerChooser" method, but when I print them after call. New assignments are not there.

in initialize:

 @Override
    public void initialize(URL url, ResourceBundle rb) {

        setPnMap();
        try {
            playerChooser();

        } catch (IOException ex) {
            System.out.println("something happened: " + ex);
        }
        print();
    }

playerChooser method:

private void playerChooser() throws IOException {
        Label secondLabel = new Label("Detectives");


//        ObservableList<String> options
//                = FXCollections.observableArrayList(
//                        "3",
//                        "4",
//                        "5"
//                );
        ComboBox comboBox = new ComboBox();
        comboBox.getItems().addAll("3", "4", "5");
        comboBox.setValue("3");

        CheckBox misterX = new CheckBox("MisterAI");
        CheckBox detectiveSelection = new CheckBox("DetectivesAI");

        misterX.setSelected(true);

        Button btnOk = new Button("OK");


        StackPane secondaryLayout = new StackPane();

        secondaryLayout.getChildren().addAll(secondLabel, comboBox, misterX, detectiveSelection);
        secondaryLayout.getChildren().add(btnOk);
        btnOk.setPrefSize(75, 25);
        secondLabel.setTranslateX(-65);
        secondLabel.setTranslateY(-50);
        comboBox.setTranslateX(30);
        comboBox.setTranslateY(-50);
        misterX.setTranslateX(-60);
        misterX.setTranslateY(0);
        detectiveSelection.setTranslateX(-50);
        detectiveSelection.setTranslateY(20);
        btnOk.setTranslateX(0);
        btnOk.setTranslateY(50);



        Scene secondScene = new Scene(secondaryLayout, 250, 150);

        // New window (Stage)
        Stage newWindow = new Stage();
        newWindow.setTitle("Second Stage");
        newWindow.setScene(secondScene);

        // Set position of second window, related to primary window.
        newWindow.setX(500);
        newWindow.setY(500);
        newWindow.setAlwaysOnTop(true);


        newWindow.show();

        btnOk.setOnAction(e -> {
            if(comboBox.getValue().equals("3")){
                detectives = 3;
            }
            else if(comboBox.getValue().equals("4")){
                detectives = 4;
            }
            else if(comboBox.getValue().equals("5")){
                detectives = 5;
            }else{
                detectives = 3;
            }
            System.out.println("Combo Box: " + detectives);

            if(misterX.isSelected()){
                this.MisterXAI = true;
                System.out.println("mister: " + this.MisterXAI);
            }else{
                this.MisterXAI = false;
            }

            if(detectiveSelection.isSelected()){
                this.DetectivesAI = true;
                System.out.println("detectives: " + this.DetectivesAI);
            }else{
                this.DetectivesAI = false;
            }
            newWindow.close();

        });

    }

expected results: 

Combo Box: 5
mister: true
detectives: true

original assignment and results:

Combo Box again: 3
mister again: true
detectives again: false