Biding StringProperty to position in list Javafx - string

Question

I am trying to create an ObservableList() to use with my Tableview. The StringData type is a class containing two SimpleStringProperty var. I want to create this list and bind each variable to an specific position of a List. Something like this:
public class DownloadService implements Runnable {
//List that will be updated
public List<SimpleStringProperty> dList = new ArrayList<SimpleStringProperty>();
public class MainScreenController implements Initializable {
//List that populates TV
private ObservableList<DataString> data = FXCollections.observableArrayList();
//tableview
#FXML
private TableView<DataString> tbl_table;
DownloadService download;
...}
public class DataString{
public final SimpleStringProperty state;
public final SimpleStringProperty sinc;
public SimpleStringProperty stateProperty() {
return state;
}
public void setState(String status) {
state.set(status);
}
public SimpleStringProperty sincProperty() {
return sinc;
}
public void setSinc(String sinc) {
this.sinc.set(sinc);
}
}
On MainScreenController I try to do this:
DataString s = new DataString();
s.state.bind (download.dList.get(data.size()));
s.sinc.bind (download.dList.get(data.size()));
data.add(s);
tbl_table.setItems(data);
However, I cannot update the content of data when I update the list on DownloadService. I believe it should update the value of the column associated with the state and sinc variable everytime DownloadService updated the content of the list in each position. I am doing something wrong or is there another way to bind a StringProperty to a position on the list?
Thanks!

Answer 1

You are binding to the specific object inside the list, not to the position. If using SimpleStringProperty in dList isn't strict requirement, than you can use Bindings.stringValueAt():
StringBinding binding = Bindings.stringValueAt(dList, index);
s.state.bind(binding);
If you really need SimpleStringProperty, you can implement custom StringBinding, something like this:
class CustomStringBinding extends StringBinding {
private ObservableList<SimpleStringProperty> op;
private int index;
public CustomStringBinding(ObservableList<SimpleStringProperty> list, int index) {
this.op = list;
this.index = index;
super.bind(op, op.get(index));
}
#Override
public void dispose() {
super.unbind(op, op.get(index));
}
#Override
protected String computeValue() {
try {
return op.get(index).get();
} catch (IndexOutOfBoundsException ex) {
// log
}
return null;
}
#Override
public ObservableList<?> getDependencies() {
return FXCollections.singletonObservableList(op);
}
}