Earlier we shared ArrayList example and how to initialize ArrayList in Java. In this post we are sharing how to iterate (loop) ArrayList in Java.
There are four ways to loop ArrayList:
- For Loop
- Advanced for loop
- While Loop
- Iterator
Lets have a look at the below example – I have used all of the mentioned methods for iterating list.
import java.util.*; public class LoopExample { public static void main(String[] args) { ArrayList<Integer> arrlist = new ArrayList<Integer>(); arrlist.add(14); arrlist.add(7); arrlist.add(39); arrlist.add(40); /* For Loop for iterating ArrayList */ System.out.println("For Loop"); for (int counter = 0; counter < arrlist.size(); counter++) { System.out.println(arrlist.get(counter)); } /* Advanced For Loop*/ System.out.println("Advanced For Loop"); for (Integer num : arrlist) { System.out.println(num); } /* While Loop for iterating ArrayList*/ System.out.println("While Loop"); int count = 0; while (arrlist.size() > count) { System.out.println(arrlist.get(count)); count++; } /*Looping Array List using Iterator*/ System.out.println("Iterator"); Iterator iter = arrlist.iterator(); while (iter.hasNext()) { System.out.println(iter.next()); } } }
Output:
For Loop 14 7 39 40 Advanced For Loop 14 7 39 40 While Loop 14 7 39 40 Iterator 14 7 39 40
In the comment section below, Govardhan asked a question: He asked, how to iterate an ArrayList using Enumeration. Govardhan here is the code:
How to iterate arraylist elements using Enumeration interface
import java.util.Enumeration; import java.util.ArrayList; import java.util.Collections; public class EnumExample { public static void main(String[] args) { //create an ArrayList object ArrayList<String> arrayList = new ArrayList<String>(); //Add elements to ArrayList arrayList.add("C"); arrayList.add("C++"); arrayList.add("Java"); arrayList.add("DotNet"); arrayList.add("Perl"); // Get the Enumeration object Enumeration<String> e = Collections.enumeration(arrayList); // Enumerate through the ArrayList elements System.out.println("ArrayList elements: "); while(e.hasMoreElements()) System.out.println(e.nextElement()); } }
Output:
ArrayList elements: C C++ Java DotNet Perl
Govardhan says
sir how to iterate arraylist elements using Enumeration interface
Chaitanya Singh says
Hi Govardhan,
I have updated the post and added the code. You can find your answer above in the post. Let me know if you have any further question.
Govardhan says
sir I have one more question:=
1.How to find middle value of a linked list by single pass
srinath says
Use two variable, lets call them fastVariable and slowVariable.
Move the fastVariable twice the speed of slowVariable.
By the time fastVariable reach end of the list slowVariable will be at middle of the list.
Thanks.
David tolu says
how to detect duplicate values in an arrayList?
Melly says
Hello!
So I have two seperate arraylists. I am trying to display both of them on a form, but only one of them is showing up. Is it possible to loop to arrayLists and display them at the same time?
Chaitanya Singh says
Melly, You can join both the arraylists and then loop the combined arraylist to display all the elements. Refer this: How to join ArrayList?