When to use LinkedList over ArrayList in Java?

In the world of programming, choosing ways to organise your data will let you win half of the battle!

Regardless of which language we are choosing to code, we always encounter data structures. These include arrays, stacks, variables, linked lists among others. Besides these terms you can also come across other essential terms like algorithm types.

Among them the most popular and widely used type is; array and linked list.

When we are using an arraylist or a linked list, the most frequent question would be where to choose an arraylist or a linked list and how linked list is preferred in certain cases over the array list?

In this blog, we are going to uncover the vitality of these two concepts in java while stating the difference between arraylist and the linked list

Without any delay, let’s get started!

Array

An array is defined as the collection of several items that gets stored inside the contiguous memory location. The idea in this case would be to store items of the same type simultaneously. Though, the general size of any array is fixed or predefined.

To solve this problem, you may come across the two vital terms that are array list and linked list. In order to know about the classes, you should know the difference between array list and linked list.

ArrayList – An Overview

Arraylist is also touted to be the part of a collection framework. In the case of java, it is being represented in the form of java.util package. This also offers the dynamic array in java language.

An arraylist is basically similar to that of an array. Though, it may have some key differences. An arraylist has the capability to shrink or grow dramatically as its elements can be added or removed. Though, an array always has a fixed size that is determined when it gets created.

Though, it can be slow as compared to the standard array but its size can easily be manipulated whenever needed. We can easily remove or add certain items into it. This will automatically get resized in a better way.

Advantages of an arraylist includes:

• As arraylists can either grow or shrink, they are basically based on the elements they have
• They provide indexed access to all the elements. It means that you will have the ease to change or modify all the elements on the basis of their specific positions
• They have convenient methods to iterate over all the elements in a particular linked list as they can easily be used with the other APIs
• Moreover, when you decide to create an arraylist, you can specify the required data type of all its elements

Linkedlist – An Overview

Linked List is defined as a type of linear data structure in which the elements will not get stored in their respective contiguous memory locations. All of these elements will become a part of a separate memory object  alongside an address part and a data part.

Each element is referred to as the node. Because of its dynamicity and the ease of all the insertions and deletions, they are basically preferred over the arrays.

Advantages of linked list includes:

• Linked list don’t have a fixed size as it can easily change its size while allocating or deallocating the memory
• Insertion or the deletion operations are easy to do with the help of a linked list
• There will be no memory wastage in the case of a linked list as its size can increase or decrease conveniently at the run time. So you need not to worry about its size.

When do you need to use a linked list over the arraylist?

In order to check when you need to use an arraylist and the linkedlist, you need to check their commonalities.

• Both the arraylist and the linkedlist are known by the implementation of the list interface as it can either be passed with the help of a linked list or an array list
• Both of them are not considered to be synchronised as you need not to share them with multiple threads without doing any type of external synchronisation
• Both are considered as the order collection as they maintain an insertion order of all the elements

These were the basic commonalities between an arraylist and the linkedlist. However, when we talk about why we need to choose linked lists over an arraylist in java, we should know about differences between both of them.

ArrayList offers constant time for varied search operations. This list is basically used in the case when there are more search operations as compared to the add or removal operations.

However, the linked list provides a definite time for the adding or removing operations. This list is better to use in place of an arraylist especially in the case of manipulation.

A linkedlist class is basically known to implement a deque interface where you will be getting the functionality of a double queue in the linked list. Though, arraylist class may not help implement the deque interface.

We can better say that arraylist is useful to access data. But a linked list is quite beneficial to manipulate the data. Both can be implemented with the help of a list interface.

Adding any element in the arraylist() is done with the help of O[1] operation as it may not trigger the size of an array. In any case it will become the O [ log n ] array. While, any element in the linked list will be appended using the O[1] operation as it may not require any type of navigation.

Wrapping Up

From algorithm types to data structures like arraylist, linked list or integers, you will come across several essential concepts while studying programming languages like java.

In this blog we have studied the array list and the linked list in detail while uncovering their usage and which one to choose in java applications.

Take cues from this blog and fill your knowledge base!