converting java fx code into java scenebuilder - javafx

Question

I cant convert this code into scene builder...
The problem is in event handler....
I am not getting how to use the confirmCloseEventHandler event handeler in java
fx scene builder...
thanks in advance.
mainly i cant use those event handlers... in fxml controllers...
public class Javafxpopupmessage extends Application {
private Stage mainStage;
#Override
public void start(Stage stage) throws Exception {
this.mainStage = stage;
stage.setOnCloseRequest(confirmCloseEventHandler);
Button closeButton = new Button("Close Application");
closeButton.setOnAction(event ->
stage.fireEvent(
new WindowEvent(
stage,
WindowEvent.WINDOW_CLOSE_REQUEST
)
)
);
StackPane layout = new StackPane(closeButton);
layout.setPadding(new Insets(100));
stage.setScene(new Scene(layout));
stage.show();
}
private EventHandler<WindowEvent> confirmCloseEventHandler = event -> {
Alert closeConfirmation = new Alert(
Alert.AlertType.CONFIRMATION,
"Are you sure you want to exit?"
);
Button exitButton = (Button)
closeConfirmation.getDialogPane().lookupButton(
ButtonType.OK
);
exitButton.setText("Exit");
closeConfirmation.setHeaderText("Confirm Exit");
closeConfirmation.initModality(Modality.APPLICATION_MODAL);
closeConfirmation.initOwner(mainStage);
// normally, you would just use the default alert positioning,
// but for this simple sample the main stage is small,
// so explicitly position the alert so that the main window can still be
seen.
// closeConfirmation.setX(mainStage.getX());
//closeConfirmation.setY(mainStage.getY() + mainStage.getHeight());
Optional<ButtonType> closeResponse = closeConfirmation.showAndWait();
if (!ButtonType.OK.equals(closeResponse.get())) {
event.consume();
}
};
public static void main(String[] args) {
launch(args);
}
}

Answer 1

Registering some handler for the primary stage via fxml could only be done with a bad hack, since FXMLLoader only has access to objects it creates itself.
You could add a listener to the Node.scene property of some node in your scene and add a listener to the window property of that scene as soon as it's set and access the window as soon as it's assigned, which is quite complex for something that could be done using much simpler code in the start method.
Other than that hack you won't get around registering that event handler in the start method (or passing the Stage to the controller resulting in more complex code than the one posted).
As for the close button onAction event: You can use a method of your controller as handler:
fxml
<StackPane xmlns:fx="http://javafx.com/fxml" fx:controller="mypackage.MyController">
<children>
<Button text="Close Application" onAction="#close"/>
</children>
<padding>
<Insets topRightBottomLeft="100"/>
</padding>
</StackPane>
controller
package mypackage;
...
public class MyController {
#FXML
private void close(ActionEvent event) {
Node source = (Node) event.getSource();
Window window = source.getScene().getWindow();
window.fireEvent(new WindowEvent(
window,
WindowEvent.WINDOW_CLOSE_REQUEST));
}
}