JavaFX 8 How to pass and use a reference to a method that doesn't return a value? - combobox

Question

I'm trying to pass and use a method reference to another method. The reference is to a setter in a TableView's model class that accepts a String input parameter and doesn't return a value.
In my FMXL controller, I'm dynamically creating table columns that contain Combo Boxes. The code is based on James_D's solution here: Java FX ComboBoxTableCell Show In Every Cell. I pass the method reference as follows:
TableColumn<TestModel, DBComboChoice> colComboBoxField = DAOGenUtil.createComboBoxColumn
("ComboBox Field",
TestModel::comboBoxFieldProperty, //this one works
TestModel::setComboBoxField, //this one doesn't work
comboData);
I'm stuck in two places in the createComboBoxColumn method - in the method declaration and in the setOnAction.
public <S> TableColumn<S, DBComboChoice> createComboBoxColumn(String title,
Function<S, StringProperty> methodGetComboFieldProperty,
//==> <WHAT-GOES-HERE?> methodSetComboField,
ObservableList<DBComboChoice> comboData ) {
TableColumn<S, DBComboChoice> col = new TableColumn<>(title);
col.setCellValueFactory(cellData -> {
String masterCode = methodGetComboFieldProperty.apply(cellData.getValue()).get();
DBComboChoice choice = DBComboChoice.getDescriptionByMasterCode(masterCode, comboData);
return new SimpleObjectProperty<>(choice);
});
col.setCellFactory((TableColumn<S, DBComboChoice> tablecol) -> {
ComboBox<DBComboChoice> combo = new ComboBox<>();
combo.getItems().addAll(comboData);
TableCell<S, DBComboChoice> cell = new TableCell<S, DBComboChoice>() {
#Override
protected void updateItem(DBComboChoice choice, boolean empty) {
super.updateItem(choice, empty);
if (empty) {
setGraphic(null);
} else {
combo.setValue(choice);
setGraphic(combo);
}
}
};
combo.setOnAction((ActionEvent event) -> {
String masterCode = combo.getSelectionModel().getSelectedItem().getMasterCode();
//==> col.getTableView().getItems().get(cell.getIndex()).<AND-HOW-DO-I-USE-IT-TO-SET-THE-DATA-MODEL'S-FIELD-TO-masterCode?>
});
return cell ;
});
return col;
}
When I tried Function<S, Void> methodSetComboField, I got an error in the FXML controller ("method createComboBoxColumn in class DAOGenUtil cannot be applied to given types"). BiConsumer<S, String> methodSetComboField didn't generate an error but I couldn't figure out how to use it in the setOnAction.
Can anyone help please? I'm using JavaFX8, NetBeans 8.2 and Scene Builder 8.3.
DBComboChoice is a class that contains a masterCode and a masterDescription eg. "F" for "Female", "M" for "Male". The masterCode is stored in the TableView's model. The masterDescription is shown in the ComboBox. I'm loading the values from a database master table.
Here are the relevant bits from the TableView's data model class:
public class TestModel {
//...
public String getComboBoxField() {
return comboBoxField.get();
}
public void setComboBoxField(String comboBoxField) {
this.comboBoxField.set(comboBoxField);
}
public StringProperty comboBoxFieldProperty() {
return comboBoxField;
}
//...
}

Answer 1

Let's take a look at the signature available:
void setComboBoxField(String)
since you don't want to specify the instance but use TestModel::setComboBoxField, you need a functional interface with a method that accepts 2 parameters: TestModel and String. You could create such an interface yourself easily
#FunctionalInterface
public interface MyInterface<S, T> {
void call(S s, T t);
}
public <S> TableColumn<S, DBComboChoice> createComboBoxColumn(String title,
Function<S, StringProperty> methodGetComboFieldProperty,
MyInterface<? super S, ? super String> methodSetComboField,
ObservableList<DBComboChoice> comboData )
Or use the existing interface BiConsumer:
public <S> TableColumn<S, DBComboChoice> createComboBoxColumn(String title,
Function<S, StringProperty> methodGetComboFieldProperty,
BiConsumer<? super S, ? super String> methodSetComboField,
ObservableList<DBComboChoice> comboData ) {
...
methodSetComboField.accept(col.getTableView().getItems().get(cell.getIndex()), masterCode);
...
}