In this tutorial, we will learn about the Java ListIterator interface with the help of an example.
The ListIterator
interface of the Java collections framework provides the functionality to access elements of a list.
It is bidirectional. This means it allows us to iterate elements of a list in both the direction.
It extends the Iterator
interface.

The List
interface provides a listIterator()
method that returns an instance of the ListIterator
interface.
Methods of ListIterator
The ListIterator
interface provides methods that can be used to perform various operations on the elements of a list.
hasNext()
– returns true if there exists an element in the listnext()
– returns the next element of the listnextIndex()
returns the index of the element that thenext()
method will returnprevious()
– returns the previous element of the listpreviousIndex()
– returns the index of the element that theprevious()
method will returnremove()
– removes the element returned by eithernext()
orprevious()
set()
– replaces the element returned by eithernext()
orprevious()
with the specified element
Example 1: Implementation of ListIterator
In the example below, we have implemented the next()
, nextIndex()
and hasNext()
methods of the ListIterator
interface in an array list.
import java.util.ArrayList;
import java.util.ListIterator;
class Main {
public static void main(String[] args) {
// Creating an ArrayList
ArrayList<Integer> numbers = new ArrayList<>();
numbers.add(1);
numbers.add(3);
numbers.add(2);
System.out.println("ArrayList: " + numbers);
// Creating an instance of ListIterator
ListIterator<Integer> iterate = numbers.listIterator();
// Using the next() method
int number1 = iterate.next();
System.out.println("Next Element: " + number1);
// Using the nextIndex()
int index1 = iterate.nextIndex();
System.out.println("Position of Next Element: " + index1);
// Using the hasNext() method
System.out.println("Is there any next element? " + iterate.hasNext());
}
}
Output
ArrayList: [1, 3, 2] Next Element: 1 Position of Next Element: 1 Is there any next element? true
Example 2: Implementation of ListIterator
In the example below, we have implemented the previous()
and previousIndex()
methods of the ListIterator
interface in an array list.
import java.util.ArrayList;
import java.util.ListIterator;
class Main {
public static void main(String[] args) {
// Creating an ArrayList
ArrayList<Integer> numbers = new ArrayList<>();
numbers.add(1);
numbers.add(3);
numbers.add(2);
System.out.println("ArrayList: " + numbers);
// Creating an instance of ListIterator
ListIterator<Integer> iterate = numbers.listIterator();
iterate.next();
iterate.next();
// Using the previous() method
int number1 = iterate.previous();
System.out.println("Previous Element: " + number1);
// Using the previousIndex()
int index1 = iterate.previousIndex();
System.out.println("Position of the Previous element: " + index1);
}
}
Output
ArrayList: [1, 3, 2] Previous Element: 3 Position of the Previous Element: 0
In the above example, initially, the instance of the Iterator
was before 1. Since there was no element before 1 so calling the previous()
method will throw an exception.
We then used the next()
methods 2 times. Now the Iterator
instance will be between 3 and 2.
Hence, the previous()
method returns 3.