What is difference between ArrayList and LinkedList ?

An Array List is an index based data structure backed by an Array. It provides random access to its elements with a performance equal to O(1). On the other hand, a Linked List stores its data as list of elements and every element is linked to its previous and next element. In this case, the search operation for an element has execution time equal to O(n).

The Insertion, addition and removal operations of an element are faster in a Linked List compared to an Array List, because there is no need of resizing an array or updating the index when an element is added in some arbitrary position inside the collection.

A Linked List consumes more memory than an Array List, because every node in a Linked List stores two references, one for its previous element and one for its next element.