JavaFX secondary stage onCloseRequest - javafx

Question

I have a little issue close a secondary stage after clicking the close at the top right corner.
I'm using fxml with controller class, i need a way to handle this situation.
Here is what i do but i get a nullpointer exception :
#Override
public void initialize(URL location, ResourceBundle resources) {
Stage stage = (Stage) tbTabPaneHome.getScene().getWindow();
stage.setOnCloseRequest(e -> {
Platform.exit();
System.exit(0);
});
}
Because the stage not yet intialized completly, so any other ideas ?

Answer 1

Since the Scene nor the Stage are created yet, you can't call them or you get a NPE, as you already mentioned.
One way to install the event handler on the stage will be listening to changes in the sceneProperty() of tbTabPaneHome.
Once the node is added to the scene, that property will give you the Scene instance.
But the scene is not added to the Stage yet, so you need to wait till this is done, with Platform.runLater():
public void initialize() {
tbTabPaneHome.sceneProperty().addListener((obs, oldScene, newScene) -> {
Platform.runLater(() -> {
Stage stage = (Stage) newScene.getWindow();
stage.setOnCloseRequest(e -> {
Platform.exit();
System.exit(0);
});
});
});
}

Answer 2

Did you try to deal with your secondary stage entirely in the main stage controller?
I want to hide or show a help windows from a button or help menu in my main application controller. Something like the following:
public Button helpBtn;
Stage anotherStage = new Stage();
boolean secondaryInitialyzed = false;
boolean secondaryShowing = false;
public void showOrHideHelp(ActionEvent actionEvent) throws IOException {
if (!secondaryInitialyzed){
Parent anotherRoot = FXMLLoader.load(getClass().getResource("mySecondaryStage.fxml"));
anotherStage.setTitle("Secondary stage");
Scene anotherScene = new Scene(anotherRoot, 500, 350);
anotherStage.setScene(anotherScene);
secondaryInitialyzed = true;
}
if (secondaryShowing){
anotherStage.hide();
secondaryShowing = false;
helpBtn.setText("Show Help");
}
else {
anotherStage.show();
secondaryShowing = true;
helpBtn.setText("Hide Help");
}
It does work, and there might be a way for you to handle your setOnCloseRequest within the main controller.
I have the opposing issue, i.e preventing closing the secondary stage window by clicking the close at the top right corner. I'll look into setOnCloseRequest and see if there is a way there.
I also have an other unrelated problem: can I position the secondary in reference to the primary one?