Programmatically display a message next to text field in JavaFX - javafx-2

Question

I have a TextField in my JavaFX application. I want to programmatically display a message on the right side of the text (like the validation message). I thought of using Popup and setting the Label with message in that Popup. But I'm not sure how I can position this to the right side of the text field. Below is the sample code for this. Can you please help me with this?
public void start(Stage primaryStage) {
primaryStage.setTitle("JavaFX Welcome");
GridPane grid = new GridPane();
grid.setAlignment(Pos.CENTER);
grid.setHgap(10);
grid.setVgap(10);
grid.setPadding(new Insets(25, 25, 25, 25));
Text scenetitle = new Text("Welcome");
scenetitle.setFont(Font.font("Tahoma", FontWeight.NORMAL, 20));
grid.add(scenetitle, 0, 0, 2, 1);
Label userName = new Label("User Name:");
grid.add(userName, 0, 1);
TextField userTextField = new TextField();
grid.add(userTextField, 1, 1);
Label pw = new Label("Password:");
grid.add(pw, 0, 2);
PasswordField pwBox = new PasswordField();
grid.add(pwBox, 1, 2);
Label label=new Label();
label.setText("This is an error message");
final Text actiontarget = new Text();
grid.add(actiontarget, 1, 6);
final Popup popup = new Popup();
popup.getContent().add(label);
//Want to display this popup to the right of the userTextField.
Scene scene = new Scene(grid, 300, 275);
primaryStage.setScene(scene);
primaryStage.show();
}

Answer 1

After showing the stage, do
Bounds userTextFieldBounds = userTextField.getBoundsInLocal();
Point2D popupLocation = userTextField.localToScreen(userTextFieldBounds.getMaxX(), userTextFieldBounds.getMinY());
popup.show(userTextField, popupLocation.getX(), popupLocation.getY());
The localToScreen(...) method was introduced in Java 8; if you are in an earlier version you will need
Bounds userTextFieldBounds = userTextField.getBoundsInLocal();
Point2D popupLocation = userTextField.localToScene(userTextFieldBounds.getMaxX(), userTextFieldBounds.getMinY());
popup.show(userTextField,
popupLocation.getX()+scene.getX()+primaryStage.getX(),
popupLocation.getY()+scene.getY()+primaryStage.getY());