javafx fxml ComboBox Error

Question

Im trying to add a String to a javafx comboBox but i keep getting the above error :/

no suitable method found for add(String)
method Collection.add(CAP#         


        

Answer 1

this is because the ComboBox elements type is not set so it's by defauld "?". like this :

ComboBox<?> room_id = new ComboBox<>(); 

so to force the fxml ComboBox to have String values you have to add something like this :

<ComboBox fx:id="cbo_Bacteriologie_Aesculine" prefHeight="21.0" prefWidth="105.0" GridPane.columnIndex="1" GridPane.rowIndex="0">
    <items>
        <FXCollections fx:factory="observableArrayList">
            <String fx:value="string option" />
        </FXCollections>
    </items>
</ComboBox>

or set the observable list from code like this :

Java ComboBox .setItems (ObservableList < T > value)

Answer 2

Simply declare the room_id field in your controller class as

@FXML
private ComboBox<String> room_id;

If you're using

@FXML
private ComboBox<?> room_id;

room_id.getItems() returns a ObservableList<?> i.e. a ObservableList with unknown element type and String cannot be assigned to this type.