LinkedList vs ArrayDeque

In this post, we will learn the difference between LinkedList and ArrayDeque in Java. This is a frequently asked question in Java interviews for beginners. Let's dive into it.

Difference between LinkedList and ArrayDeque in Java

LinkedList ArrayDeque
LinkedList is implemented as a doubly linked list. ArrayDeque is implemented as a resizable array.
LinkedList allows null elements. ArrayDeque does not allow null elements.
LinkedList can perform all operations at both ends, but it is typically slower than ArrayDeque. ArrayDeque is faster than LinkedList for enqueue (add) and dequeue (remove) operations at both ends.
In LinkedList, every insertion or removal of an element requires a new Node object to be created or removed, increasing the time and memory overhead. In ArrayDeque, elements are added and removed without creating or destroying any placeholder objects, reducing overhead.
LinkedList uses more memory because it uses extra space for storing pointers to the next and previous elements. ArrayDeque uses less memory because it only stores the elements in a contiguous array.
LinkedList provides sequential access, i.e., to get to an element you have to traverse from the head node. This can take more time. ArrayDeque provides faster access and removal of elements as compared to LinkedList.
LinkedList in Java can also be used as a List with indices, allowing you to retrieve, add or remove elements from the middle of the list, although these operations are not as efficient. ArrayDeque is primarily used as a Deque (Double ended queue) and lacks the ability to access elements using indices.
In LinkedList, the 'size()' method is a constant-time operation. In ArrayDeque, the 'size()' method is also a constant-time operation.