ArrayList: Iteration using ListIterator

ListIterator

The Iterator provides very limited capabilities as we can iterate only in the forward direction and we can’t update or insert an element to the list while iterating. To overcome these problems, we can use ListIterator. The listIterator() method returns an object of type ListIterator which can then be used to iterate the ArrayList.

Below are the methods that are available in the ListIterator interface.

1. hasNext() — This method is used to check if there is a next element in the list when the list is iterated in the forward direction.

2. next() — This method returns the next element in the list and advances the cursor position.

3. hasPrevious() — This method is used to check if there is a next element in the list when the list is iterated in the backward direction.

4. previous() — This method returns the previous element in the list and moves the cursor position backward.

5. nextIndex() — This method returns the index of the element that would be returned by a subsequent call to next(). It returns the list size if the list iterator is at the end of the list.

6. previousIndex() — This method returns the index of the element that would be returned by a subsequent call to previous(). It returns -1 if the list iterator is at the beginning of the list.

7. remove() — This method removes the last element that was returned by next() or previous() from the list. This call can only be made once per call to next() or previous(). It can be made only if add() has not been called after the last call to next() or previous().

8. set(E e) — This method replaces the last element returned by next() or previous() with the specified element. This call can be made only if neither remove() nor add() have been called after the last call to next() or previous().

9. add(E e) — This method inserts the specified element into the list. The element is inserted immediately before the element that would be returned by next(), if any, and after the element that would be returned by previous(), if any.

The below example shows ListIterator working.