Difference Between ArrayList and LinkedList

Collections are advantageous for data storage. The size of a typical array is fixed. Occasionally, it is necessary to design arrays that can expand as necessary. Java and other programming languages provide collections. It is a framework consisting of a collection of classes and interfaces. It functions as a container for a collection of items. Collections provide the storing, updating, and retrieval of sets of items. It facilitates the manipulation of data structures like lists, sets, trees, and maps. The list is a Collection foundation interface. ArrayList and LinkedList are two collection foundation classes. They implement both the collection and List interfaces. This article compares and contrasts ArrayList vs LinkedList. ArrayList is a class that extends AbstractList that implements the List interface, internally storing data items in a dynamic array. LinkedList is a class that extends AbstractSequentialList that implements the List, Deque, and Queue interfaces, which internally store data items via a double-linked list. This is the fundamental difference between ArrayList and LinkedList.

In this blog, before diving into the differences between ArrayList and LinkedList, let's discuss their definition.

What is ArrayList?

The ArrayList class is used to create dynamic arrays. In contrast to a standard array, the size of a dynamic array is not fixed. An object built using the ArrayList class may store a collection of items in the list. The capacity grows automatically, allowing the programmer to add items to the list. The ArrayList class is an extension of AbstractList, which implements the List interface. Therefore, ArrayList may use the List interface's functions. get () method is used to retrieve items. The add() function may be used to add entries to a list. The remove() function eliminates an item from a list.

Features:

• Java ArrayList class may have duplicate items.
• The ArrayList class in Java preserves insertion order.
• The Java ArrayList class lacks synchronization.
• ArrayList in Java permits random access since the array is indexed.

Advantages:

• You may define ArrayList as a re-sizable array.
• Elements may be introduced or removed at a specific place.
• Numerous methods exist inside the ArrayList class for manipulating stored items.

Disadvantages:

• ArrayList may be defined as a resizable array.
• Elements may be introduced or removed at a specific place.
• Numerous methods exist inside the ArrayList class for manipulating stored items.

What is LinkedList?

Similar to ArrayList, LinkedList is used to store data components dynamically. An object formed using the LinkedList class can hold a list of list items. The capacity grows automatically, allowing the programmer to add items to the list. It stores data internally using a doubly-linked list. The data in a doubly linked list is kept as nodes. Each node is composed of two connections. The first connection connects to the preceding node. The following link leads to the subsequent node in the series.

The LinkedList class implements the List interface and extends the AbstractSequentialList class. Therefore, LinkedList may use the methods of the List interface. The get() function may be used to get list items. The add() function may be used to add entries to a list. The remove() function eliminates an item from a list.

Features:

• The first node in a linked list is referred to as the list's head.
• The last node of the linked list points to None, indicating that it is the final node.
• Unlike arrays, the members of a linked list are not kept in contiguous memory regions.

Advantages:

• In linked lists, insertion and deletion are very efficient.
• Expanding a linked list takes continuous time.
• To implement stacks and queues, as well as to represent trees and graphs.

Disadvantages:

• Linked lists make more use of pointers, making them more sophisticated and requiring more memory.
• Searching for an element is expensive and O(n) time complicated.
• In singly linked lists, navigating takes longer, and reverse traversing is not feasible.

ArrayList vs LinkedList

Conclusion

In conclusion, ArrayList and LinkedList are both implementations of the List interface in Java and offer a way to store and manipulate a collection of elements. However, they differ in terms of how they store and access the elements, as well as their performance characteristics.

ArrayList uses an array to store its elements and provides constant time performance for read and write operations at the expense of slower insertion and deletion. LinkedList, on the other hand, uses a doubly-linked list data structure to store its elements and provides faster insertion and deletion at the expense of slower read and write operations.

Both ArrayList and LinkedList have their own trade-offs and it is important to choose the right one based on the specific requirements of your application. In general, ArrayList is a good choice when read and write operations are more frequent and order is important, while LinkedList is a better choice when frequent insertion and deletion is required.

Related Questions

1. Is LinkedList remove element faster than ArrayList?

LinkedList is quick for adding and removing items, but accessing a single element is expensive. Accessing a particular member in an ArrayList is quick, but adding to either end and deleting from the center may be sluggish.

2. Can ArrayList have duplicate values?

ArrayList permits duplicate values, but HashSet prohibits duplicates. ArrayList preserves the order of the objects in its collection, while HashSet is an unordered collection that does not preserve order.

3. Is LinkedList a list or a queue?

In essence, a LinkedList is a Queue; it has all of the capabilities of a Queue and more. Keep in mind that a Queue is not a LinkedList, since LinkedList are constructed and enlarged from Queues.

4. Is the linked list FIFO or LIFO?

A singly-linked list may be LIFO or FIFO (first-in, first-out) (first-in-first-out). Using the LIFO approach, nodes will be added and removed from the same end of the list. If it use FIFO, nodes will be appended to one end and removed from the other. In addition, the linked list is sortable.