Problem using FormatStringConverter in ComboBox.setConverter in javafx - javafx-2

Question

I have to use a combobox to associate a list of values (key, Value). Key is the value to be stored in the database, Value is the description to be displayed in the combobox.
For example:
Key / value
C1 Code one
C2 Choice two
C3 Choice three
...
Retrieving, for example, the selected value 'Choice two' I would like to receive the code C2.
For storing the elements in items I defined the ComboVal class.
Defining my combobox, I am stuck on the definition of the setConverter function.
The compiler gives me the following error:
Error: (1093, 49) java: constructor FormatStringConverter in class javafx.util.converter.FormatStringConverter cannot be applied to given types; required: java.text.Format; found: no arguments
reason: actual and formal argument lists differ in length
Code:
class ComboVal {
String[] dato = {null, null};
ComboVal (String Key, String Value)
{
setValue(Key, Value);
}
ComboVal ()
{
setValue(null, null);
}
String getValue ()
{
return dato[1];
}
String getKey ()
{
return dato[0];
}
void setValue (String Key, String Value)
{
dato[0] = Key;
dato[1] = Value;
}
}
classe myclass {
....
/*
Parameter ctrl is a List containing information for dynamic creation of combobox
*/
void mothod (List ctrl)
{
VBox box = new VBox();
box.getChildren().add(new Label(ctrl. label));
ObservableList items = FXCollections.observableArrayList();
ComboBox<ComboVal> cb = new ComboBox<>();
cb.setId(ctrl.name);
cb.setItems(items);
//----->>> compiler report error in the next row <<<<<<<<
cb.setConverter(new FormatStringConverter<ComboVal>() {
#Override
public String toString (ComboVal object)
{
return (object.getValue());
}
#Override
public ComboVal fromString (String string)
{
return null;
}
});
ctrl.options.forEach((k, v) -> {items.add(new ComboVal(k, v));});
cb.setCellFactory(new Callback<ListView<ComboVal>, ListCell<ComboVal>>() {
#Override
public ListCell<ComboVal> call (ListView<ComboVal> p)
{
return new ListCell<ComboVal>() {
#Override
protected void updateItem (ComboVal item, boolean empty)
{
super.updateItem(item, empty);
if (item == null || empty)
{
setGraphic(null);
}
else
{
setGraphic(new Text(item.getValue()));
}
}
};
}});
box.getChildren().add(cb);
}

Answer 1

The FormatStringConverter class needs to be constructed with a Format parameter. You however constructed it with no parameters.
Supply a Format, like this for example:
Format format = new MessageFormat("Bla bla");
cb.setConverter(new FormatStringConverter<ComboVal>(format);
The FormatStringConverter defines its own toString and fromString methods already, and will use the given format to parse and display the values. I doubt this is what you want as this is pretty limited.
So I think you'd be better of just using a regular StringConverter and provide the custom implementations for toString and fromString.