JavaFX: Dynamically added VBox does not show up - javafx

Question

I'm working on a project that requires a "tabled" representation of VBoxes. My hierarchical layout of the application is GridPane -> VBox (in one of the Cells) -> VBoxes (that display different datasets on top of each other) -> Data. I have two Scenes.
Data is displayed on Scene 1. The user can add data through a form and by clicking a button on Scene 2. Then, the added data should be displayed below the existing data as a VBox within the parent-VBox on Scene 1 again.
Here is the code that will make it clear:
My Scene 1 .fxml file looks the following (Simplified):
<GridPane fx:id="grid" fx:controller="application.Controller">
[here: ColumnConstraints]
<children>
<VBox fx:id="parentBox" GridPane.columnIndex="0" GridPane.rowIndex="1"/>
<Button fx:id="goToScene2" text="+" onAction="#goToScene2"/>
</children>
</GridPane>
Scene 2 just has a button and a TextField:
<GridPane fx:id="grid" fx:controller="application.AddDataController">
[here: ColumnConstraints]
<children>
<Button fx:id="addData" text="add" onAction="#bAddData"/>
<TextField fx:id="data"/>
</children>
</GridPane>
My Scene 1 controller (controller) looks like this:
public class Controller implements Initializable {
#FXML Button goToScene2;
#FXML VBox parentBox;
#Override
public void initialize(URL location, ResourceBundle resources) {
}
public void addData(String s) {
Label lbl = new Label(s);
VBox dataBox = new VBox();
dataBox.setPadding(new Insets(15, 5, 15, 5));
dataBox.setSpacing(5);
dataBox.setMaxHeight(80);
dataBox.getChildren().add(lbl);
parentBox.getChildren().add(dataBox);
}
}
This is designed as it is because the dataBox contains more elements than the label, but that doesn't seem relevant to me in this context.
My Scene 2 controller (addDataController) looks like this:
#FXML Button addData;
#FXML TextField data;
#FXML protected void bAddData(){
String content = data.getText();
FXMLLoader fxmlLoader = new FXMLLoader();
Pane p = fxmlLoader.load(getClass().getResource("scn1.fxml").openStream());
Controller cont = (Controller) fxmlLoader.getController();
cont.addData(content);
}
So, when one clicks on the Add-Data-Button in Scene 2, the triggered method passes the entered data to the Controller of Scene 1. This is because the new data should be displayed in Scene 1 now.
I feel like the logic does not work (edited here), because when I ask for
System.out.println(parentBox.getChildren().size();
before and after the data was added, it always has one single Child, even though it should have one more...
If I artificially fill a String-Array and move everything from addData to(String s) to Initialize(...), it does work and the data shows up as VBoxes in the parent-VBox.
I didn't post the main class, because loading Controllers and Scene change is not an issue.
Thank you all very very much for your help! :)

Answer 1

Just to provide more detailed information, together with an idea, that I don't know how to implement.
This is my main class:
#Override
public void start(Stage primaryStage) {
currentStage = primaryStage;
Parent root = FXMLLoader.load(getClass().getResource("Scene1.fxml"));
scene1 = new Scene(root);
}
Could I load the controller at this point and make a getter that passes the Controller? So I'd only have one single instance of it throughout the program.
I tried inserting:
FXMLLoader fxmlLoader = new FXMLLoader();
fxmlLoader.load(getClass().getResource("Scene1.fxml").openStream());
Controller controller = (Controller) fxmlLoader.getController();
after the
Parent root ...
line. But that's loading the .xml file twice. How can I nicely connect both parts?
Thanks so much for you patience!
EDIT:::::::::
The following code worked for me:
#Override
public void start(Stage primaryStage) {
currentStage = primaryStage;
FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("Scene1.fxml"));
Parent root =(Parent) fxmlLoader.load();
controller = (Controller) fxmlLoader.getController();
}
Now, I can ask the main class for controller and it always passes that single instance.
Thank you for pointing me to the right direction! :)