Solved: javafx get window in controller

get window in controller In the world of Java programming, one common challenge that developers face is how to get a window in the controller class. Controllers are the backbone of any JavaFX application as they manage the application’s data and overall functionality. Today, we’ll cover such an issue and learn how to implement a solution, discuss the step-by-step process, dive into related libraries and functions, and explore similar situations where this knowledge might be helpful. So, let’s start our journey into the world of Java programming and window controllers.

JavaFX is a popular library for creating rich graphical user interfaces for modern applications. One of its many powerful features is the ability to separate the application’s logic into controllers, making the code more organized and easier to maintain. However, sometimes a developer may need to work with the window directly, and herein lies the challenge of getting the window from the controller. We’ll look into that with our solution that employs the Stage class while taking advantage of JavaFX’s flexibility and versatility.

Getting the Window in Controller

The core of the solution lies in the Stage class – one of JavaFX’s primary building blocks. A Stage represents a top-level window in a JavaFX application and consists of a visual area for your application’s scenes. To get the window in the controller, you should pass the reference of the stage to the controller once it’s created.

public class Main extends Application {
    public void start(Stage primaryStage) throws Exception {
        FXMLLoader loader = new FXMLLoader(getClass().getResource("MainWindow.fxml"));
        Parent root = loader.load();
        MainWindowController controller = loader.getController();

        primaryStage.setTitle("Sample Application");
        primaryStage.setScene(new Scene(root));;

    public static void main(String[] args) {

First, the FXMLLoader loads the FXML file, which describes the user interface of the application. Then, using the getController() method, we obtain a reference to the MainWindowController and pass the primaryStage reference to the controller, allowing it to access the window directly.

The MainWindowController class would look like this:

public class MainWindowController {
    private Stage window;

    public void setWindow(Stage window) {
        this.window = window;
    // Other methods go here

Now, the controller has complete access to the window and can perform various operations on it based on the application’s requirements.

JavaFX Libraries and Functions

JavaFX is a powerful library that offers many features to create engaging, visually appealing applications. Along with the Stage class, it provides numerous other classes and components for crafting the perfect UI for your application. Some of the essential components include:

  • Scene: A container for all visual components of the application. Every Stage has a Scene, and the Scene is responsible for managing the visual hierarchy of the user interface.
  • FXMLLoader: Loads the .fxml files that define the user interface, making it easier to design complex UI layouts and separate UI logic from backend code.
  • Node: A Node represents any visual element in a JavaFX application, such as labels, buttons, and layouts. All visual components in the application inherit from Node.
  • Parent: A specialized Node subclass that allows one or more child nodes, which can be arranged according to the parent’s specific layout rules.

Handling Similar Cases

Getting the window in the controller is just one use case for working with JavaFX libraries and functions, but there are many other scenarios where this knowledge can be very helpful. For instance:

  • Dynamic Content: Understanding how to work with window instances can help create applications that dynamically switch between different content inside a single window, improving user experience.
  • Custom Window Appearance: Direct access to the window in the controller allows the developer to change its appearance based on user preferences or application requirements, such as altering colors, transparency or shape.
  • Window Control: Working closely with the window instance, a developer can provide users more control over the window, such as resizing, minimizing, maximizing, or closing a window programmatically.

In conclusion, knowing how to get a window in the controller is a valuable skill for JavaFX developers. By understanding how to work with the Stage class and similar components in JavaFX, developers can enhance the capabilities of their applications and create more effective and polished user interfaces.

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