如何在主应用程序之前启动登录？

Question

问题： 我的GUI项目中有两个扩展javafx.Application的类：一个是应实现主板的GUIcontroller，另一个是LoginGUI，应仅实现Login窗口。

我想在从GUIcontroller中启动主板之前，并且只有在登录成功后，才从GUIcontroller中启动LoginGUI。 但是怎么办呢？

GUIController

public class GUIController extends Application implements ViewInterface {

private Parent rootAdrenaline;
private Stage primaryStage;
private LoginGUI loginGUI;


//starts the mainBoard GUI
@Override
public void start(Stage primaryStage) throws Exception {

    rootAdrenaline = FXMLLoader.load(getClass().getClassLoader().getResource("MapGUI.fxml"));
    this.primaryStage = new Stage();
    this.primaryStage.setTitle("Adrenaline's Board");
    this.primaryStage.setScene(new Scene(rootAdrenaline, 1189, 710));
    this.primaryStage.setOnCloseRequest(event -> {exitApp(event);});
    this.primaryStage.show();
}

public void displayLogin(){

    this.loginGUI = new LoginGUI();
    this.loginGUI.launchLogin();
}

public void setLoginButton(){

    loginButton.setOnAction(event -> tryToConnect());
}

public void tryToConnect(){//connect to server}

LoginGUI

public class LoginGUI extends Application {

public synchronized void start(Stage primaryStage) throws Exception {

    Parent adrenalineLog = FXMLLoader.load(getClass().getClassLoader().getResource("LoginGUI.fxml"));
    Scene scene = new Scene(adrenalineLog, 600, 470);

    primaryStage.setTitle("Adrenaline Login");
    primaryStage.setScene(scene);
    primaryStage.show();

}

public void launchLogin() {
    launch();
}