如何以正确的方式多次关闭并打开javafx gui ..来自另一个类

Question

如何从another.class多次打开javafx gui，其中another.class就像本地gui和通过远程接口远程服务器之间的控制器... 例如：

 public class JavaFxPlay extends Application {
public static void main(String[] args) {
    launch();
}

@Override
public void start(Stage primaryStage) throws Exception {
    Label label = new Label("This is the main GUI");
    VBox root = new VBox();
    root.getChildren().add(label);
    Scene scene = new Scene(root, 300, 200);
    primaryStage.setScene(scene);
    primaryStage.setTitle("Main");

    showSecondaryStage();
    primaryStage.show();
}

private void showSecondaryStage() {
    Stage newStage = new Stage();
    newStage.setTitle("Login");
    Label label = new Label("Login here");
    VBox root = new VBox();
    root.getChildren().add(label);
    Scene scene = new Scene (root, 100, 50);
    newStage.setScene(scene);
    newStage.showAndWait();
}

}

然后从其他类这样的东西

public class SetUp 
{
  //field 1
  //field 2

   public SetUp()
   {
    }
    public sessionSetUp()
    {
       //some code, then launch main gui
        Application.launch(JavaFxPlay.class); //this works

      //main gui closes and exits after finishing
      //some more code then i need to show the secondary stage of example

      Application.launch(JavaFxPlay.showSecondaryStage()); //of course this is wrong, how to do this is my problem!!!
    }
public static void main(String[] args)
{
    // TODO Auto-generated method stub
    SetUp setup = new SetUp();
    setup.sessionSetUp();

}

}