JavaFX Treeview shows no items

Question

I try to implement an TreeView in my JavaFX App. But unfortenatly no items are showed, but i cannot find an issue. I search for some example and did it like them.

I put

Answer 1

You shouldn't assign new instance to the this.treeview because this field was already initialized by the FXLoader. So instead of this.treeview = new TreeView<>(root); you need simply to set the root item this.treeview.setRoot(root);