ArrayList Vs LinkedList in Java

Last Updated: 15 January, 2023

ArrayList and LinkedList are both classes of the Collection Framework, and both classes implement the List interface.

Both the classes have some common features, such as maintaining the insertion order of elements, and both are by default non-synchronized.

However, there are many differences between the ArrayList and LinkedList classes that are given below.

👉 ArrayList

ArrayList in Java is a concrete class of the List interface that was introduced in the JDK 1.2 version and is available in the java.util package. An ArrayList is used to store a dynamically sized collection of elements. An ArrayList grows in size automatically. Elements can be added, modified, and removed from an ArrayList whenever there is a need.

Java ArrayList Class Declaration

public class ArrayList<E>
extends AbstractList<E>
implements List<E>, RandomAccess, Cloneable, Serializable

Here, E defines the type of elements that the List will contain.

Java ArrayList important features:

ArrayList extends the AbstractList class and implements the List, RandomAccess, Cloneable, and Serializable interfaces.
ArrayList is an ordered collection, so it maintains the insertion order of the elements.
ArrayList allows duplicate and null elements.
By default, an ArrayList is not synchronized. If multiple threads try to modify an ArrayList at the same time, then the final outcome will be non-deterministic.
ArrayList does not accept primitive types like int, char, etc. We need to use boxed types like Integer, Character, Boolean, etc.
ArrayList allows random access because the array works on an index basis.
Each ArrayList instance has a capacity. The capacity is the size of the array used to store the elements in the list. The default capacity is 10.
ArrayList performance is a bit slower than LinkedList because a lot of shifting operations are needed if we insert or delete elements in the middle of the ArrayList.

👉 LinkedList

The LinkedList class was introduced in the Java 1.2 version and is available in the java.util package. It is a doubly-linked list implementation of the List and Deque interfaces.

LinkedList Class Declaration

public class LinkedList<E>
extends AbstractSequentialList<E>
implements List<E>, Deque<E>, Cloneable, Serializable

Here, E defines the type of elements that the List will contain.

Important features of LinkedList:

LinkedList underlined data structure is a Double Linked List.
LinkedList contains duplicate values.
LinkedList maintains the insertion order of elements.
Each element in a LinkedList is known as a node, and each node contains three fields:
1. The previous element's address
2. Actual Data
3. The next element's address
By default, the LinkedList class is not synchronized.

👉 ArrayList and LinkedList have the following differences:

ArrayList	LinkedList
ArrayList internally uses a dynamic array to store the elements.	LinkedList internally uses a doubly linked list to store the elements.
ArrayList implements the List interface. Therefore, this acts as a list.	LinkedList implements both the List interface and the Deque interface. Therefore, it can act as both a list and a deque.
ArrayList is slow because array manipulation is slower.	LinkedList is faster than node-based as there is not much bit shifting required.
ArrayList is best for storing and accessing elements from the list.	For manipulating the elements, LinkedList is the best choice.
ArrayList allocates contiguous memory locations.	LinkedList does not allocate contiguous memory locations.
The default capacity of an ArrayList is 10.	LinkedList has no default capacity. An empty list is created when a LinkedList is initialized.

👉 Example of ArrayList and LinkedList in Java

Example 1: A sample Java program of ArrayList

  import java.util.ArrayList;
  class ArrayListExample {
    public static void main(String[] args){
      // Creating ArrayList
      ArrayList<String> countries = new ArrayList<>();
      // Adding elements in ArrayList
      countries.add("India");
      countries.add("Canada");
      countries.add("US");
      countries.add("England");
      // Printing ArrayList elements
      System.out.println("ArrayList Elements: " + countries);
    }
  }

Output

ArrayList Elements: [India, Canada, US, England]

Example 2: A sample Java program of LinkedList

  import java.util.LinkedList;
  class LinkedListExample {
    public static void main(String[] args){
      // Creating LinkedList
      LinkedList<String> countries = new LinkedList<>();
      // Adding elements in LinkedList
      countries.add("India");
      countries.add("Canada");
      countries.add("US");
      countries.add("England");
      // Printing LinkedList elements
      System.out.println("LinkedList Elements: " + countries);
    }
  }

Output

LinkedList Elements: [India, Canada, US, England]

That's all guys, hope this Java article is helpful for you.

Happy Learning... 😀

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