How to use BreadCrumbBar in ControlsFX (JavaFX 8)

I'm a Java beginner trying to use BreadCrumbBar from ControlsFX to make a navigation bar in a desktop application I'm making using JavaFX 8. I can't seem to be able to get the bar to work the way I want to, and searching for a tutorial online yielded no results. I've found the API but it doesn't help much.

My code is attached below:

@FXML
private BreadCrumbBar bread;

private TreeItem<String> tree, tree1, tree2;

@FXML
private void initialize(){
    tree = new TreeItem<String>("Log In");
    tree1 = new TreeItem<String>("Language Selection");
    tree2 = new TreeItem<String>("Patient List");
    tree.getChildren().addAll(tree1, tree2);
    bread.setSelectedCrumb(tree);
}

public void refresh(){
    bread.setSelectedCrumb(tree.nextSibling(bread.getSelectedCrumb()));
}

The bar appears as it should for the log in screen showing only "Log In" as the selected crumb.I'm calling refresh from the main class every time I want to shift to the next breadcrumb button but the bar just disappears when I move on from the first screen. Should't it set the selected crumb to the next sibling of tree i.e. tree1 ?

If anyone knows how to configure the autonavigation function that would be really helpful too. (possibly more helpful than sorting out my own code if it's easy to implement)

Thanks!

The BreadCrumbBar use a tree to display the navigation, so you should create the TreeItem in consequence.

Here is an example of a tree with 3 levels :

TreeItem<String> root = new TreeItem<String>("Root");
        
TreeItem<String> item1 = new TreeItem<String>("Item 1");
TreeItem<String> item11 = new TreeItem<String>("Item 1.1");
TreeItem<String> item12 = new TreeItem<String>("Item 1.2");
        
item1.getChildren().addAll(item11, item12);
        
TreeItem<String> item2 = new TreeItem<String>("Item 2");
        
root.getChildren().addAll(item1, item2);

Then you have a tree graphicaly represented like this :

                   <item11>
                 /
         <item1>
       /         \
<root>             <item12>
       \
         <item2>

When you use the BreadCrumbBar.setSelectedCrumb(TreeItem<?>) you select

the bottom-most path node (the node on the most-right side in terms of the bread crumb bar)

So if you use breadcrumb.selectedCrumbProperty().set(root); you will get :

And if you use breadcrumb.selectedCrumbProperty().set(item11); you will get :

Hope it helps, I actually am trying to figure out how it works too ^^