ArrayList vs LinkedList: Difference and Comparison

ArrayList is a resizable array found in java. util packages and stands a difference with built-in array due to modification of size and comes with more derived elements.

LinkedList is known for its data structure linearity and is not stored at a location contagious like ArrayList. The differences in them make it unique to use in different algorithm situations in Java and other coding.  

Key Takeaways

1. ArrayList uses a dynamic array to store elements, providing fast random access and efficient resizing.
2. LinkedList uses a doubly-linked list to store elements, allowing for efficient insertion and deletion operations.
3. Both are Java Collection classes for data storage, with different performance characteristics based on the required operations.

ArrayList vs LinkedList

ArrayList internally uses a dynamic array to store its elements. It is slow for data manipulation and better for storing and accessing data hence it only acts as a list. LinkedList uses a doubly linked list to store its elements. It is faster and better for manipulating data and can act as both a list and a queue.

As said that ArrayList plays an immense part in the collection framework, which leads to dynamic arrays in Java performed by various elements and operations.

Some basic operations are always performed in ArrayList, like adding and changing elements and inheriting AbstractList class. The initialization of size in ArrayList tends to increase and shrink based on the collection. 

LinkedList is known for its dynamic size and the notion of easy inserts and deletes, unlike ArrayList. LinkedList is represented by a pointer to the head (node) to make sure whether it is impactful or null. They are also linked through addresses and are preferred over elements of the array.

Comparison Table

Parameter of Comparison	ArrayList	LinkedList
Usage	A dynamic array is used to store elements internally.	A double-linked list is used to store elements internally.
Manipulation	Manipulation is slow and takes more time.	Manipulation is faster and takes the least time.
Implementation	ArrayList implements only List.	LinkedList implements List and Queue.
Access	ArrayList is better when an application wants to store and access data.	LinkedList works faster in the manipulation of the stored data.
Performance	ArrayList performs 0(1).	LinkedList performs 0(n).

What is ArrayList? 

ArrayList uses its distinctive dynamic array for storing the elements with no size limit. This improvises that one can add and remove these elements anytime required. ArrayList is much more flexible than the substantial array used in Java before, and now, Arraylist is found in java. util package.

Moreover, the ArrayList uses an array data structure and so maintains an index-based system for its elements. This amplifies in making it faster for searching an element in the list.  

ArrayList has some duplicate elements also that are implemented and act on the list. This happens so that we can use all the methods of the List interface here as its key features.

The ArrayList also manages and maintains the internal order insertion and inherits the AbstractList but is non-synchronized. An important fact about ArrayList is its random access due to the work of an array based on an index.  

ArrayList() is used to build an empty array list, ArrayList(Collection<? Extends E>c) is used to build an array list initialized by the elements of collection “c”, and ArrayList(int capacity) is used in array list where there is specialized initial capacity. 

It is a tat bit slower in manipulation compared to LinkedList because whenever the element is omitted, it causes many shifting, which affects it. Hence, it extends in sequential order for the list interface. 

What is LinkedList?

A LinkedList is connected through links in a sequence of data structures. It contains items that are linked with one another from one end to another to work sequentially and in every manner.

LinkedList is preferable to an array and is second most preferably used after an array. LinkedList implements a doubly linked list. It requires the crosspiece to go through all the elements for searching it. LinkedList is widely used.

To understand the concept of LinkedList certain terms require to be understood. The terms are Link, where each link in the linked list can store data known as elements.

There is Next, where each link is connected from each end in the data. Last, there is LinkedList which is connected from one end link to the first link for the LinkedList to work, which is referred to as First. 

There are various types of LinkedList such as Simple LinkedList for item navigation forward only, Double LinkedList for navigation of items forward and back, and Circular Linked List to form a circular link from the last item link to the first element and next and e first element link to the last element and previous.

The basic operations of LinkedList for elements are insertion, deletion, display, search and delete. 

Main Difference between ArrayList and LinkedList: 

1. In LinkedList, elements can be added indefinitely, whereas, in an ArrayList, elements get filled or gets resized. 
2. It is easier to remove elements from the LinkedList, whereas, in ArrayList, it is not easy as it leaves empty spaces which occupy computer memory for no use. 
3. ArrayList allows random access to elements contained internally. LinkedList, however, only allows sequential access to the elements. 
4. LinkedList uses more storage space in the computer’s memory than ArrayList, as each node in the list contains the data and reference link to the next mode. It is unlike ArrayList. 
5. ArrayList should be used for small lists where almost every number of items on the list is known. On the other hand, LinkedList should be used for large lists of data where there is a change in the total number of items. 

References

1. https://ieeexplore.ieee.org/abstract/document/6606620/
2. https://dl.acm.org/doi/abs/10.1145/1529282.1529391

Last Updated : 16 July, 2023