ArrayList vs LinkedList in Java

What is ArrayList?

ArrayList is a resizable array implementation in Java’s Collection Framework. It allows dynamic storage of elements and provides fast access using indexes.

Example:

import java.util.ArrayList;
class ArrayListExample {
    public static void main(String[] args) {
        ArrayList list = new ArrayList<>();
        list.add("Apple");
        list.add("Banana");
        list.add("Orange");
        System.out.println(list);
    }
}
  

What is LinkedList?

LinkedList is a doubly-linked list implementation of the List and Deque interfaces. Each element points to the previous and next node, allowing efficient insertions and deletions.

Example:

import java.util.LinkedList;
class LinkedListExample {
    public static void main(String[] args) {
        LinkedList list = new LinkedList<>();
        list.add("Apple");
        list.add("Banana");
        list.add("Orange");
        System.out.println(list);
    }
}
  

Differences between ArrayList and LinkedList

Aspect	ArrayList	LinkedList
Data Structure	Resizable array	Doubly linked list
Access Time	Fast random access (O(1))	Slow random access (O(n))
Insertion / Deletion	Costly in middle (O(n))	Fast in middle (O(1))
Memory Usage	Less memory overhead	Higher memory (pointers for prev/next)
Use Case	Frequent access, less modification	Frequent insertion/deletion

Advantages

ArrayList: Fast access, simple implementation

LinkedList: Efficient insertion/deletion, can act as Queue/Deque

Limitations

ArrayList: Slow insertion/deletion in middle, resizing overhead

LinkedList: Slower access, more memory usage

Best Practices

Use ArrayList when frequent access and fewer modifications are required.

Use LinkedList when frequent insertions/deletions in middle are expected.

Understand memory trade-offs between the two implementations.