It seems this method does not work as expected:

http://docs.oracle.com/javafx/2/api/javafx/collections/FXCollections.html#observableList%28java.util.List,%20javafx.util.Callback%29

Expected result: changes to one of the Observables trigger an update change in the ListChangeListener, as described in the JavaDoc.

However, the change does not trigger.
See also here:
https://forums.oracle.com/forums/thread.jspa?messageID=10447614
(The usage seems to be correct)
I think the problem is, that the extractor callback is not called for elements being already in the List, which you pass.


If I use this method instead:
http://docs.oracle.com/javafx/2/api/javafx/collections/FXCollections.html#observableArrayList%28javafx.util.Callback%29

it works, but here is another bug:
In the ListChangeListener, the change.wasAdded() returns true, which is wrong in my opinion. It should return false - nothing was added.
change.wasUpdated returns also true (which is correct), all other was* methods return false (also correct).


Sample:

import javafx.beans.Observable;
import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.collections.FXCollections;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
import javafx.util.Callback;

import java.util.ArrayList;
import java.util.List;


public class TestApp2 {

    public static void main(String[] args) {

        System.out.println("testObservableListWithExtractor");
        testObservableListWithExtractor();

        System.out.println("testObservableArrayListWithExtractor");
        testObservableArrayListWithExtractor();

    }

    private static void testObservableListWithExtractor() {
        List<MyObservable> arrayList = new ArrayList<MyObservable>();
        arrayList.add(new MyObservable("Test"));
        arrayList.add(new MyObservable("Test2"));

        ObservableList<MyObservable> list = FXCollections.observableList(arrayList, new Callback<MyObservable, Observable[]>() {
            @Override
            public Observable[] call(MyObservable myTreeData) {
                // This is only called for elements added to "list", not elements which already exist in "arrayList".
                System.out.println("Extractor: " + myTreeData.name.get());
                Observable[] observables = new Observable[1];
                observables[0] = myTreeData.nameProperty();
                return observables;
            }
        });
        list.add(new MyObservable("Test3"));

        list.addListener(new ListChangeListener<MyObservable>() {

            @Override
            public void onChanged(Change change) {
                while (change.next()) {
                    System.out.println("Added:" + change.wasAdded());
                    System.out.println("Removed:" + change.wasRemoved());
                    System.out.println("Permutated:" + change.wasPermutated());
                    System.out.println("Replaced:" + change.wasReplaced());
                    System.out.println("Updated:" + change.wasUpdated());
                }
            }
        });

        list.get(0).nameProperty().set("Hi");
    }

    private static void testObservableArrayListWithExtractor() {
        ObservableList<MyObservable> list = FXCollections.observableArrayList(new Callback<MyObservable, Observable[]>() {
            @Override
            public Observable[] call(MyObservable myTreeData) {
                Observable[] observables = new Observable[1];
                observables[0] = myTreeData.nameProperty();
                return observables;
            }
        });
        list.add(new MyObservable("Test"));
        list.add(new MyObservable("Test2"));


        list.addListener(new ListChangeListener<MyObservable>() {

            @Override
            public void onChanged(Change change) {
                while (change.next()) {
                    System.out.println("Added:" + change.wasAdded());
                    System.out.println("Removed:" + change.wasRemoved());
                    System.out.println("Permutated:" + change.wasPermutated());
                    System.out.println("Replaced:" + change.wasReplaced());
                    System.out.println("Updated:" + change.wasUpdated());
                }
            }
        });

        list.get(0).nameProperty().set("Hi");
    }

    private static class MyObservable {

        public MyObservable(String name) {
            this.name.set(name);
        }

        public StringProperty name = new SimpleStringProperty();

        public StringProperty nameProperty() {
            return name;
        }
    }
}