How to loop ArrayList in Java

In this guide, you will learn how you can loop through an ArrayList in Java. In the ArrayList tutorial, we learned that it belongs to java.util package and unlike arrays, it can grow in size dynamically. There are several different approaches to iterate an ArrayList, lets discuss them with examples:

1. Using a for Loop

One of the easiest way to iterate through an ArrayList is by using for loop:

import java.util.ArrayList;

public class ArrayListExample {
    public static void main(String[] args) {
        ArrayList<String> names = new ArrayList<>();
        names.add("Chaitanya");
        names.add("Rahul");
        names.add("Aditya");

        // names.size() returns size of ArrayList and get()
        // method returns the element present at specified index
        for (int i = 0; i < names.size(); i++) {
            System.out.println(names.get(i));
        }
    }
}

2. Using an Enhanced for Loop (for-each)

The enhanced for loop provides a simple and more readable way to iterate through all the elements in an ArrayList. Let’s take the same example that we have seen above but with for-each loop instead of for loop.

import java.util.ArrayList;

public class ArrayListExample {
    public static void main(String[] args) {
        ArrayList<String> names = new ArrayList<>();
        names.add("Chaitanya");
        names.add("Rahul");
        names.add("Aditya");

        for (String name : names) {
            System.out.println(name);
        }
    }
}

3. Using an Iterator

One of the limitations with for-each loop is that you cannot remove an element while iterating. An Iterator provides a way to iterate a collection, and it allows you to remove an element while iterating.

import java.util.ArrayList;
import java.util.Iterator;

public class ArrayListExample {
    public static void main(String[] args) {
        ArrayList<String> names = new ArrayList<>();
        names.add("Chaitanya");
        names.add("Rahul");
        names.add("Aditya");

        Iterator<String> iterator = names.iterator();
        while (iterator.hasNext()) {
            System.out.println(iterator.next());
        }
    }
}

4. Using a ListIterator

A ListIterator allows you to traverse the list in both directions. You can also modify the list during iteration:

import java.util.ArrayList;
import java.util.ListIterator;

public class ArrayListExample {
    public static void main(String[] args) {
        ArrayList<String> names = new ArrayList<>();
        names.add("Chaitanya");
        names.add("Rahul");
        names.add("Aditya");

        ListIterator<String> listIterator = names.listIterator();
        // Traversing forward
        while (listIterator.hasNext()) {
            System.out.println(listIterator.next());
        }
        
        // Traversing backward
        while (listIterator.hasPrevious()) {
            System.out.println(listIterator.previous());
        }
    }
}

5. Using Streams (Java 8 and later)

Stream API is introduced in Java 8. I have covered it in detail here: Java 8 Streams Tutorial. You can also loop through an ArrayList elements using stream.

import java.util.ArrayList;

public class ArrayListExample {
    public static void main(String[] args) {
        ArrayList<String> names = new ArrayList<>();
        names.add("Chaitanya");
        names.add("Rahul");
        names.add("Aditya");

        names.stream().forEach(System.out::println);
    }
}