Controller 类中的 FileChooser - SceneBuilder JavaFX

Question

I'm trying to code the functionality of a button created using SceneBuilder. I found the "Code" section in Scene builder and set the name of the method that will launch when I click on the button (eg fileSelector). In the method I should use FileChooser variable(I need to take an image from the PC and save it to a "File" variable).

I copied the sample controller skeleton and paste it to my Controller class. Now I don't know how to implement the method, because I need a Stage variable to use with the FileChooser variable, but the stage variable is given for the public void start(Stage primaryStage) method.

My Main Class

package application;

import java.io.IOException;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;    

public class MainExample extends Application  {
    @Override
    public void start(Stage primaryStage) throws IOException {
        Pane firstPane = FXMLLoader.load(MainExample.class.getClassLoader().getResource("buttonExample.fxml"));
        Scene firstScene = new Scene(firstPane);
        primaryStage.setScene(firstScene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}

My Controller Class

package application;

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Button;

public class MyController {

    @FXML
    private Button selectFile;

    @FXML
    void fileSelector(ActionEvent event) {
        FileChooser fileChooser = new FileChooser();
        File file = fileChooser.showOpenDialog(stage);
    }
}

The FXML from the button

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.Pane?>

<Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="135.0" prefWidth="280.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.MyController">
    <children>
        <Button fx:id="selectFile" layoutX="102.0" layoutY="55.0" mnemonicParsing="false" onAction="#fileSelector" text="SelectFile" />
    </children>
</Pane>

Answer 1

You need a Window instance to show a FileChooser dialog, you can get it from the event like this:

@FXML
void fileSelector(ActionEvent event) {
    Window window = ((Node) (event.getSource())).getScene().getWindow();
    FileChooser fileChooser = new FileChooser();
    File file = fileChooser.showOpenDialog(window);
    event.consume();
}