Creates a new javafx.beans.binding.StringBinding that contains the element of an javafx.collections.ObservableList at the specified position. The StringBinding will hold null if the index points behind the ObservableList.

Parameters:

op		the ObservableList
index		the position in the List

Returns:  the new StringBinding

Exceptions:

NullPointerException		if the ObservableList is null
IllegalArgumentException		if (@code index < 0)

Since:  JavaFX 2.1