Switching To Primary Scene When Secondary Scene Is Closed - javafx

Question

I am using JavaFX 11 and a newbie.
I have a single stage with two scenes: a primary scene that shows on start and a secondary scene that is switched to and shown when I press a certain button on the main scene. On the secondary scene, I want to be able to switch back to the main scene when I click the close X button on the top right of the window instead of having the entire application close.
I currently have a method for the cancel button that looks like this:
public void cancelButtonPushed(ActionEvent event) throws IOException {
Parent parent = FXMLLoader.load(getClass().getResource("ExampleMainScreen.fxml"));
Scene scene = new Scene(parent);
Stage window = (Stage) ((Node) event.getSource()).getScene().getWindow();
window.setScene(scene);
window.show();
}
This method allows me to switch back to the main scene when the Cancel button is pushed. However, I am lost trying to find something that can be used any time the user clicks the close X on the secondary scene.

Answer 1

First, get the terminology right, my guess is that you have two Stages. Scenes can be displayed inside those.
Second, Scene Builder (and the FXML it produces) does not manage stages, it only constructs nodes (and event handling for those nodes) that are placed inside scenes. So, you won't find the hooks you need to integrate with the window close functions in SceneBuilder or FXML.
Third, when a user wants to close a window (a stage is a kind of window), then an event will be emitted, which you can action onCloseRequest.
Fourth, somehow you have already managed to create a second stage, probably by calling new Stage(). This will provide you with a reference to the stage which you can set your close request on:
Stage secondaryStage = new Stage();
Stage setScene(secondaryScene);
secondaryStage.setOnCloseRequest(e -> primaryStage.show());
This will show your primary stage (which I guess you hid earlier), when the secondary stage is being closed, but before it has actually closed.
Next, read up on the Application lifecycle, specifically see the section which references Platform.setImplicitExit(boolean implicitExit):
If this attribute is true, the JavaFX runtime will implicitly shutdown when the last window is closed; the JavaFX launcher will call the Application.stop() method and terminate the JavaFX application thread. If this attribute is false, the application will continue to run normally even after the last window is closed, until the application calls exit(). The default value is true.
Note, that, you probably don't need to explicitly set the implicit exit flag if you handle the stage switching as outlined previously, but I provide the info for you in case you need to understand it.
Finally, consider whether you really should be creating new stages for your application and this particular task or just replacing the content in a single stage (similar to how a web browser works).