Difference between ArrayList & LinkedList that everyone should know

difference between arraylist and linkedlist

Introduction

In software engineering, the ways that we choose to organize our data is half the battle. When it comes to managing the data, many tools could do the job for us. ''Understanding of WHEN TO USE? WHY USE IT? WHERE TO USE? is the key!''

Regardless of the language we code in, one of the first things that we encounter are data structures, which are the different ways we can organize our data; arrays, stacks, linked lists, variables, etc., are all different types of data structures. These are just the tip of the iceberg for data structures. In this blog, we will check the difference between arraylist and linkedlist

Linked List

A Linked List is a linear data structure where the elements are stored at non-contiguous memory locations. In simple terms, it can be defined as a collection of objects randomly stored in the memory. These objects are called nodes.

A node contains two fields: a data field and a reference link. The data field contains the data stored at that particular address. And the reference link contains the pointer, which contains the address of the next node in the memory. The last node of the linked list contains a pointer to null.

Linked List

Attempt some questions related to Linked List on our CodeStudio platform.

Advantages of a Linked List

It does not have any fixed size and can change its size at runtime by allocating and deallocating memory.
Insertion and deletion operations are easier in a linked list.
No memory wastage as the size of the linked list can increase or decrease in size at run time.

Disadvantages of a Linked List

Extra memory space is required to store the pointers along with the data.
Random access is not possible as it is not index-based.
In the linked list, reverse traversing is difficult. In the case of a doubly-linked list, it's easier, but extra memory is required for the back pointer, decreasing memory efficiency.

ArrayList

In Java, an ArrayList is a dynamic data structure that allows you to store a collection of elements of the same data type. It is an implementation of the List interface, which means that it allows for indexed access to its elements, and it also provides various methods to add, remove, and manipulate elements in the list.

An ArrayList is similar to an array, but with a few key differences. One of the main differences is that an ArrayList can grow or shrink dynamically as elements are added or removed, whereas an array has a fixed size that is determined when it is created.

Another difference is that an ArrayList provides methods to add or remove elements at specific positions in the list, whereas with an array, you would need to manually shift all the elements after the insertion or removal point.

Overall, an ArrayList is a flexible and convenient way to store and manipulate collections of elements in Java.

Advantages of an ArrayList

Dynamic size: Unlike arrays, ArrayLists can grow or shrink dynamically based on the number of elements they contain. This makes them more flexible and convenient to work with.
Indexed access: ArrayLists provide indexed access to their elements, which means that you can easily retrieve or modify elements at a specific position in the list.
Efficient insertion and removal: ArrayLists provide methods to add or remove elements at specific positions in the list, and they handle the shifting of elements automatically. This makes it more efficient than manually shifting elements in an array.
Easy iteration: ArrayLists provide convenient methods for iterating over the elements in the list, such as using a for-each loop or the Iterator interface.
Compatible with other Java APIs: Since ArrayLists implement the List interface, they can be used with other Java APIs that accept lists as inputs or return lists as outputs.
Type safety: When you create an ArrayList, you can specify the data type of the elements it will contain. This ensures type safety and can prevent errors at runtime.
Memory efficient: ArrayLists are more memory efficient than arrays since they only allocate the amount of memory needed to store the elements they contain. In contrast, arrays have a fixed size that is determined when they are created, even if some of the elements are. empty.

Disadvantages of an ArrayList

ArrayLists consume more memory than arrays because they need to store additional information, such as the size of the list and the capacity of the underlying array.
Inserting or removing elements in the middle of an ArrayList can be slow because it requires shifting all the elements after the insertion or removal point.
ArrayLists are not thread-safe by default, which means that if multiple threads try to modify the same ArrayList at the same time, it can result in unexpected behaviour or errors.
ArrayLists can be less efficient than arrays for certain operations, such as iterating over the elements in order, because they involve additional method calls and object instantiations.
Since ArrayLists are implemented using arrays, there is a risk of running into the same issues as arrays when the capacity of the underlying array needs to be increased, such as performance degradation and memory fragmentation.

Difference between Arraylist and Linkedlist

	ArrayList	LinkedList
Internal Implementation	Uses an array to store elements	Uses a doubly linked list to store elements
Access time	O(1) for random access, O(n) for insertion and deletion	O(n) for random access, O(1) for insertion and deletion
Memory usage	More memory is used for maintaining the size of the array	Less memory is used since only the elements and pointers are stored
Iteration performance	Fast, since elements are stored in contiguous memory locations	Slower, since elements are not stored in contiguous memory locations
Adding elements	Can be slow if the size of the array needs to be increased to accommodate new elements	Fast, since only pointers need to be updated
Removing elements	Can be slow if elements need to be shifted to fill the gap left by the removed element	Fast, since only pointers need to be updated
Thread safety	Not inherently thread-safe, but can be made thread-safe using synchronization.	Not inherently thread-safe, but can be made thread-safe using synchronization.
Use cases	Best suited for scenarios where random access is required and the list will not be modified frequently	Best suited for scenarios where insertion and deletion are frequent, and random access is not required.

Frequently Asked Questions

Why insertion and deletion are faster in a linked list?

Insertion and deletion are faster in a linked list because less memory needs to be manipulated.

Which is better to use ArrayList or LinkedList?

ArrayLists are better suited for scenarios where random access is required, whereas LinkedLists are preferred for frequent insertion and deletion of elements. The choice depends on the specific use case and performance requirements.

Why use LinkedList over ArrayList?

LinkedLists are preferred over ArrayLists for scenarios where frequent insertion and deletion of elements is required, as these operations are faster with LinkedLists. LinkedLists can also be more memory-efficient than ArrayLists.

Where are Linkedlist used in real life?

LinkedLists are used in real-life applications where frequent insertion and deletion of elements is required, such as in music and video streaming applications to maintain a playlist and in image processing software to maintain a list of filters applied to an image.

Conclusion

With this discussion, this blog attempted to compare the data structures Linked List vs Arrays, along with the advantages and disadvantages.

Now that you know the data structures well go ahead and attempt some questions based on them on our CodeStudio Platform!

Recommended Reading:

To study more about Linked Lists, refer to Applications Of Linked Lists.

We hope you found this blog useful. Feel free to let us know your thoughts in the comments section.

Difference between ArrayList and LinkedList