How to setCellValueFactory return type for ArrayList - javafx

Question

I have following error in this code: Cannot infer type arguments for ReadOnlyListWrapper<>
How should my return type look like? I need to save arraylist for each node in all columns. But I can not return it.
for (Entry<String, String> ent : dc.getSortedOrgAll().entrySet()) {
TreeTableColumn<String, ArrayList<String>> col = new TreeTableColumn<>(
ent.getValue());
col.setCellValueFactory(new Callback<TreeTableColumn.CellDataFeatures<String, ArrayList<String>>, ObservableValue<ArrayList<String>>>() {
#Override
public ObservableValue<ArrayList<String>> call(
CellDataFeatures<String, ArrayList<String>> param) {
TreeMap<String, List<String>> temp = (TreeMap<String, List<String>>) dc
.getFuncTypeOrg().clone();
ArrayList<String> result = new ArrayList<>();
for (int i = 0; i < temp.size(); i++) {
List<String> list = temp.firstEntry().getValue();
String key = temp.firstEntry().getKey();
// root.getChildren();
if (list.get(1).equals("Papier")) {
System.out.println(list.get(1));
}
if (list.get(1).equals(param.getValue().getValue())
&& list.get(5).equals(col.getText())) {
result.add(list.get(2));
if(list.size()==9)
result.add(list.get(list.size()-1));
else result.add("White");
} else {
temp.remove(key);
// result = null;
}
}
return new ReadOnlyListWrapper<>(result);
}
});

Answer 1

ReadOnlyListWrapper<T> implements ObservableValue<ObservableList<T>>, which isn't what you need, as you declared the callback to return an ObservableValue<ArrayList<T>> (T is just String here).
So I think you just need
return new ReadOnlyObjectWrapper<ArrayList<String>>(result);
and you can probably omit the generic type:
return new ReadOnlyObjectWrapper<>(result);
Just a comment: I think you could make your life much easier by defining some actual data model classes, instead of trying to force your data into various collections implementations.