Change the property of a rectangle by using another class JavaFX

I'm working on a project and I want a rectangle to appear when I press a button. However, I want to do this by directing the button click to a different class. Here is what I've tried:

Here is my first class, "Main"

static boolean btnClicked = false;
	@Override		
	
public void start(Stage primaryStage) {
	
	Button btn = new Button("Make Popup Visible");
	
	Rectangle menu = new Rectangle(40,40,200,200);
	menu.setFill(Color.BLACK);
	menu.setOpacity(0);
	
	btn.addEventHandler(MouseEvent.MOUSE_CLICKED,(MouseEvent e) ->{
		AddRect.showMenu();
	});
	
	if(btnClicked == true) {
		menu.setOpacity(1);
	}
	
	Group root = new Group();
	root.getChildren().addAll(btn, menu);
	Scene scene = new Scene(root,400,400);
	scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
	primaryStage.setScene(scene);
	primaryStage.show();

}

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

And my second class, "AddRect"

public class AddRect {
	static void showMenu() {
		Main.btnClicked = true;
	}
}

However, this isn't working, and I don't know why. Can somebody help me? I don't even know if this is the best way to do it (Using two classes), but if there is a better way please let me know. Thanks in advance!

I figured it out! I just had to move the conditional inside the EventHandler

	btn.addEventHandler(MouseEvent.MOUSE_CLICKED,(MouseEvent e) ->{
		AddRect.showMenu();
		if(btnClicked == true) {
			menu.setOpacity(1);
		}
	});