The LinkedList class in Java’s Collections Framework is a powerful and flexible implementation of both the List and Deque interfaces. Unlike ArrayList, which is a dynamic array, LinkedList is a doubly-linked list structure. This fundamental difference dictates its performance characteristics and ideal use cases.

What is a Doubly-Linked List?

A LinkedList stores its elements in individual nodes. Each node contains three parts:

1. The data (the element itself).
2. A pointer to the next node in the sequence.
3. A pointer to the previous node in the sequence.

Because it is a doubly-linked list, traversal can happen in both forward and backward directions.

Internal Structure Visualization

HEAD                               TAIL
  ↓                                 ↓
[null|Data1|→] ↔ [←|Data2|→] ↔ [←|Data3|null]