Difference : ArrayList vs LinkedList

Array List and Linked List both implements List interface. But which one to use when calls for a discussion. So lets look at the ways in which they differ to decide when to use ArrayList or LinkedList. 

Both differ based on following parameters:

1.       Insertion or Deletion of element

If there is need for lot of insertion or deletion of a elements in the List, then prefer Linked List as it provides faster insertion or deletion operation in comparison to Array List.

Reason: 

Array List requires lots of index shifting to be done for any insertion or deletion operation to be performed as a result performance time increases. Take a glimpse of insertion(13 needs to be inserted at index 2) in diagram given below:

Linked List does not require shifting of many nodes. It just effects three nodes. One which is to be inserted. And the other two are between which it needs to be inserted. Take a glimpse of insertion(node having element 2 needs to be inserted between 1 and 3) in diagram given below.

Since lots of element don't need to be shifted for performing insertion or deletion operation in case of Linked List (which is in case of Array List), so it performs faster insertion and deletion operation. 

2.       Searching element from List

If one needs to search or get element from the List then for better performance opt for Array List as it provides faster search operation in comparison to Linked List.

3.       Memory consideration

Linked List consumes more memory space in comparison to Array List.

Reason : 

Linked List has to maintain extra memory space for storing address data in both forward & backward pointer for each and every node apart from storing the element. Array List does not bother at all about storing any address detail so no extra memory requirement. 

      4.    Storage Mechanism

ArrayList uses dynamic array to store the elements.  

LinkedList uses doubly linked list to store the elements.

      5. Role

Arraylist can only perform the role of a List as it implements only List interface.

LinkedList can perform the role of both List and Queue as it implements both List and Deque interfaces

Example

package ListExample;

import java.util.ArrayList;

import java.util.LinkedList;

import java.util.List;

public class ListExample {

      public static void main(String[] args) {

            //create ArrayList

            List<String> arrayList = new ArrayList<String>(); 

            //add element to ArrayList

            arrayList.add("Rajneesh");

            arrayList.add("Shweta");

            arrayList.add("Anup");

            //create LinkedList 

           List<String> linkedList = new LinkedList<String>();

            //add elements to LinkedList

            linkedList.add("Puja");

            linkedList.add("Mukesh");

            linkedList.add("Titli");

      }

}

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