List in Java vs. ArrayList in Java: What's the Difference?
Edited by Aimie Carlson || By Janet White || Published on February 14, 2024
In Java, List is an interface defining a sequential collection, while Array List is a resizable-array implementation of the List interface.
Key Differences
The List in Java is an interface that provides a blueprint for data structures that represent a sequential collection of elements, without specifying any specific implementation. ArrayList, on the other hand, is a concrete class that implements the List interface, using a dynamic array to store its elements.
A key characteristic of the List interface in Java is that it allows for the creation of a collection of elements that can be accessed in a sequential manner, including insertion and deletion operations. ArrayList, as an implementation of List, provides these functionalities with the added benefit of a dynamically resizable array, which can grow or shrink as needed.
The List interface in Java supports polymorphism, meaning that it can reference an object of any class that implements it, such as ArrayList, LinkedList, or Vector. ArrayList is specifically an implementation that focuses on fast random access of elements and efficient management of its size.
When it comes to usage, the List interface in Java is often used when you want to maintain a collection that can change in size, without being concerned about the specific details of how this is achieved. ArrayList is chosen when one needs a simple and efficient implementation for a resizable array.
The List interface in Java is part of the java.util package and defines methods for manipulating the elements of a collection, such as adding, removing, and accessing elements. ArrayList inherits these methods and provides its own implementations that optimize for speed and memory utilization.
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Comparison Chart
Type
Interface
Concrete Class
Implementation
Abstract, needs a concrete implementation
Implements List using a resizable array
Size Flexibility
Depends on the implementation
Dynamically resizable
Performance
Varies based on implementation
Fast random access, efficient size management
Use Case
Used when different types of lists are needed
Used for simple, efficient list operations
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List in Java and ArrayList in Java Definitions
List in Java
List allows sequential access to its elements.
The List was iterated to process each element.
ArrayList in Java
ArrayList is preferred for lists where frequent access to random elements is needed.
For quick lookups, I chose ArrayList over LinkedList.
List in Java
List in Java can be implemented by various classes like ArrayList or LinkedList.
For my project, I chose to implement the List interface using a LinkedList.
ArrayList in Java
ArrayList is part of the java.util package.
To use ArrayList, I imported java.util.ArrayList in my code.
List in Java
List supports operations like insertion, deletion, and iteration over elements.
The List interface made it easy to add and remove items.
ArrayList in Java
ArrayList in Java is a resizable array implementation of the List interface.
I used an ArrayList to store dynamically changing data.
List in Java
List in Java is an interface for ordered collections.
I created a List in Java to store the names of participants.
ArrayList in Java
ArrayList allows random access to its elements.
Retrieving an element from the ArrayList was efficient due to its array nature.
List in Java
List in Java is part of the java.util package.
I imported java.util.List for my collection handling.
ArrayList in Java
ArrayList grows automatically as elements are added to it.
The ArrayList expanded automatically when more items were added beyond its initial capacity.
FAQs
When should I use List in Java?
Use List when you want flexibility to switch between different List implementations.
What is a List in Java?
List is an interface in Java representing an ordered collection of objects.
How do you add an element to an ArrayList?
Use the add() method to add elements to an ArrayList.
When is ArrayList the preferred choice?
Choose ArrayList for efficient random access and dynamic resizing.
How do you initialize an ArrayList?
Initialize it using new ArrayList<>().
What is an ArrayList in Java?
ArrayList is a resizable-array implementation of the List interface in Java.
Can I store different types of objects in a List or ArrayList?
Yes, both can store different types of objects, but using generics is recommended for type safety.
Can ArrayList contain duplicate elements?
Yes, ArrayList can contain duplicates.
Can I access elements in a List by index?
Yes, if the List implementation supports it, like ArrayList.
Is List in Java ordered?
Yes, List maintains the insertion order of elements.
Are there any limitations of using ArrayList?
ArrayList can be less efficient for large lists or when inserting/removing elements from the beginning or middle.
How do you iterate over an ArrayList?
Use a for loop, enhanced for loop, or iterator.
Is ArrayList thread-safe?
No, ArrayList is not thread-safe.
How do you convert an ArrayList to an array?
Use the toArray() method.
How do you remove an element from an ArrayList?
Use the remove() method to remove elements from an ArrayList.
What happens if an ArrayList exceeds its initial capacity?
It automatically resizes to accommodate additional elements.
How does ArrayList handle null elements?
ArrayList allows null elements.
Can I create a List of primitive types?
List can only hold objects, use wrapper classes for primitive types.
Can I sort an ArrayList?
Yes, use Collections.sort() to sort an ArrayList.
About Author
Written by
Janet WhiteJanet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.
Edited by
Aimie CarlsonAimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.
