javafx - How to access @FXML components of one controller from another controller? -

i using afterburner build simple application. have 3 packages package main, package inwards , package outwards.

main.fxml has anchor pane in loading inwards.fxml @ application start.

now inwards.fxml has button action load outwards.fxml in anchor pane of main.fxml.

but doing giving me null pointer exception.

thank you.