How can I set a default value in a ComboBox
using FXML?
I don't think it's possible in the FXML. You will need to do it in the initialization of the component, in the controller, for example using the following line cbo_Bacteriologie_Aesculine.getSelectionModel().setSelectedIndex(1);
for selecting the element Bezig.
But if you find a way to do it in FXML, I am interested.
EDIT : It is possible in FXML. You can see it in Guedolino's answer (https://stackoverflow.com/a/14436371/1344424), which should become the right answer to this question.