Difference between ArrayList and LinkedList in Java

Author:
In this article, we will discuss the difference between ArrayList and LinkedList in Java. This is one of the frequently asked Java interview questions in Java interviews.

Java provides us with two List implementations, ArrayList and LinkedList, to store and manipulate a list of objects. While they both are implementations of the List interface and share some properties, they also have some significant differences. Here, we will take a deep dive into the differences between ArrayList and LinkedList in Java and discuss the most appropriate use cases for each.

YouTube Video

This difference is explained very well in below YouTube video:

Difference between ArrayList and LinkedList in Java

Underlying Data Structure 

The most fundamental difference between ArrayList and LinkedList lies in the underlying data structure. ArrayList internally uses a dynamic array to store its elements. When the array becomes full, a new array is created, and the old array is copied into the new one, which allows ArrayList to resize dynamically.
List<String> arrayList = new ArrayList<>();
arrayList.add("Apple");
arrayList.add("Banana");
System.out.println(arrayList);  // Output: [Apple, Banana]
On the other hand, LinkedList internally used a doubly-linked list to store the elements.
List<String> linkedList = new LinkedList<>();
linkedList.add("Apple");
linkedList.add("Banana");
System.out.println(linkedList);  // Output: [Apple, Banana]

Memory Usage 

ArrayList: In ArrayList, elements are stored in contiguous memory locations, which results in less memory usage. 

LinkedList: In LinkedList, each element stores two extra fields for the address of the next and the previous node, thus consuming more memory.

Performance: Access, Insertion, and Deletion 

ArrayList: ArrayList provides faster access to elements since it uses an array data structure and elements can be accessed directly using their indices. However, insertion and deletion operations are slower in ArrayLists because, during these operations, the array may need to be resized or all elements may need to be shifted.

LinkedList: In contrast, LinkedList provides faster insertion and deletion operations. Inserting or removing an element only requires changing the pointer location in the two adjacent nodes of the linked list. However, access operations are slower because to access an element, we have to start from the head (or tail) and traverse the list until we find it.

When to Use ArrayList and LinkedList?

The decision to use ArrayList or LinkedList in Java depends on your specific use case, but here are some general guidelines: 

Use ArrayList when: 

Random Access is required: ArrayList provides faster access to any element since it maintains an index-based system. 

Less insertion and deletion operations: If your primary operations are fetching elements and you have fewer insert and delete operations, ArrayList offers a better choice. This is because removal or insertion in ArrayList requires shifting of elements, which is costly. 

Use LinkedList when: 

Frequent insertion/deletion: LinkedList is preferable when you have more insertion or deletion operations. Manipulation with LinkedList is faster than ArrayList because it uses a doubly linked list, so no bit shifting is required in memory. 

Fewer search operations: If there are fewer get() and set() operations in your application, LinkedList could be a better choice. 

Memory is not a constraint: As we know, LinkedList consumes more memory than ArrayList, so if memory is not a constraint, then LinkedList can be considered.

Summary

The below diagram summaries the between ArrayList and LinkedList in Java:


Related Java Interview Articles

Related Interview Questions and Answers:

ArrayDeque vs LinkedList in Java ConcurrentHashMap vs HashMap in Java PriorityQueue vs LinkedList in Java WeakHashMap vs HashMap in Java IdentityHashMap vs HashMap in Java CopyOnWriteArraySet vs HashSet in Java SynchronizedMap vs ConcurrentHashMap in Java TreeMap vs LinkedHashMap in Java EnumSet vs HashSet in Java EnumMap vs HashMap in Java Queue vs Stack in Java NavigableMap vs SortedMap in Java NavigableSet vs SortedSet in Java Iterable vs Collection in Java Difference between final, finally, and finalize in Java Difference between Error and Exception in Java Checked Exception vs Unchecked Exception in Java Difference between Object and Class in Java Difference between Runnable and Thread in Java Difference between == and equals() method in Java static variable vs instance variable in Java Abstract Class vs Interface in Java fail-fast vs fail-safe Iterators in Java Difference between break and continue in Java Difference between constructors and methods in Java Difference between throws and throw in Java synchronized block vs synchronized method in Java while loop vs do-while loop in Java Immutable vs Mutable objects in Java Difference between Annotation and Enum in Java static block vs static method in Java Marker Interface vs Functional Interface in Java Shallow Copy vs Deep Copy in Java Composition vs Inheritance in Java Difference between volatile and transient in Java Difference between sleep() and wait() in Java Difference between & and && in Java Difference between | and || in Java Switch-Case vs If-Else in Java? Default Method vs Static Method in Java Interfaces For Loop vs Enhanced For Loop (for-each) in Java Difference between Servlet and JSP in Java Difference between ORM and JDBC in Java hashCode() vs equals() in Java Difference between Throwable and Exception in Java Difference between import and package in Java Daemon Thread vs User Thread in Java Difference between literal and constant in Java Difference between this and super Keyword in Java Lambda vs Anonymous Class in Java Stack vs Heap Memory in Java Runnable vs Callable in Java Difference between Path and File in Java NIO count() vs length() in Java Stream API Intermediate vs Terminal Operations in Java Stream API Executor vs ExecutorService in Java Primitive Data Type vs Reference Data Type in Java Compiler vs Interpreter in Java Difference between WAR and JAR in Java Dependency Injection vs Factory Pattern in Java Difference between PUT and POST in Java REST API Static Nested Class vs Inner Class in Java Difference between GET and POST in Java Web Services Encapsulation vs Abstraction in Java JPA vs Hibernate in Java with Example @Bean vs @Component in Spring @Autowired vs @Resource in Spring Difference between JDBC and JPA Difference between Spring Security and OAuth2 Difference between Spring Cloud and Spring Boot Difference between Spring Boot and Microservices @RequestParam vs @PathVariable in Spring Boot @Query vs NamedQuery in JPA Spring Data JPA vs Hibernate in Java with Example @Controller vs @RestController in Spring Boot

Comments

Post a Comment

Leave Comment