Iterable Interface

It is easy to declare that IndexedList ADT is iterable:

/**
 * IndexedList ADT.
 * @param <T> the base type of the items in the IndexedList.
 */
public interface IndexedList<T> extends Iterable<T> {

  // No changes were made to the declaration of operations.

}

By inheritance, the IndexedList ADT now contains the following method declaration (inherited from the Iterable interface):

/**
  * Returns an iterator over elements of this collection.
  *
  * @return an Iterator.
  */
Iterator<T> iterator();

Any class that implements IndexedList (such as ArrayIndexedList) must provide an implementation for the iterator method.