Size of a BorderPane left side

[Peter Penzov]

I wan to get the size of the left side of a BorderPane In JavaFX 8. I
tested this:


mainPanel.getRight().getBoundsInLocal().getWidth();



I think that this is not the correct way. Can you show me how I can do this
if it's possible?



I tested this code:



I get the width of the Left side of a BorderPane, then I set the width of a
TabPane:



BorderPane mainPanel new BorderPane();
tabPane.setPrefWidth(mainPanel.getRight().getBoundsInLocal().getWidth());




I get NPE. Can you help me to correct my mistake? I want when I resize the
Center of the BorderPane to update the size of the TabPane(shrink it or
expand it dynamically).