I have the following FXML:
@Groostav: In case we programmatically "know" the value that should appear as selected (for example, we landed in an edit form), we can do the following:
1) Add a new item with index 0 (that is, the element we need to show as selected):
myChoiceBox.getItems().add(0, ItemObtainedProgrammatically);
2) Show the item as selected (since we already know it's at position 0):
myChoiceBox.getSelectionModel().select(0);
Probably this qualifies as a dirty hack, but it works. The con: You have the same item twice in your choicebox