How to obtain the button size created by JavaFX ?

Question

Here the codes:
ToggleButton tb1 = new ToggleButton("Minor");
System.out.println(tb1.getWidth());
System.out.println(tb1.getPrefWidth());
The output is :
0.0
-1.0
But in Swing,
JButton tb1 = new JButton("Minor");
System.out.println(tb1.getPrefferedSize().width);
The output is 109 which is I want to obtain.
How can we get the size of the button created by "new Button() ..." as in Swing ? I strongly hope the answer is yes, because I find that function in Swing very useful.
Thanks
(Note: I discover that after the code "primaryStage.show()", we can get the correct button width by using button.getWidth(), but when we use button.getPrefWidth() we still get -1.0, the value undesired.)

Answer 1

Thanks for your prompt. I have been read that discussion. But their responses are not very appropriate for me.
Rectangle rect = new Rectangle(); 
rect.widthProperty().bind(tb1.widthProperty().add(tb2.widthProperty())); 
is what I want to obtain.
And
final Button button = new Button("Play"); 
final Scene snapScene = new Scene(button); 
snapScene.snapshot(null); 
System.out.println(button.getWidth()); 
is also a very good solution for me.