Data Structures and Algorithms in Java[1].pdf - Fulvio Frisone

Code Fragment 6.15: The iterator() method of
class NodePositionList.
Position Iterators
For ADTs that support the notion of position, such as the list and sequence ADTs,
we can also provide the following method:
positions(): Return an Iterable object (like an array list or node
list) containing the positions in the collection as elements.
An iterator returned by this method allows us to loop through the positions of a
list. To guarantee that a node list supports this method, we could add it to the
PositionList interface, as shown in Code Fragment 6.16. Then we could, for
example, add an implementation of this method to the NodePositionList, as
shown in Code Fragment 6.17. This method uses the NodePositionList
class itself to create a list that contains the positions of the original list as its
elements. Returning this list of positions as our Iterable object allows us to
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