Linked List Data Structure in Java

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What is a Linked List?

A linked list is a linear collection of data elements, with each element pointing to the next one in the sequence. This structure allows efficient insertions and deletions compared to an array, making it useful in certain scenarios.
A linked list has the following properties.
  • Successive elements are connected by pointers
  • The last element points to NULL
  • Can grow or shrink in size during the execution of a program
  • Can be made just as long as required (until systems memory exhausts)
  • Does not waste memory space (but takes some extra memory for pointers). It allocates memory as the list grows.

Linked List Representation

A linked list can be visualized as a chain of nodes, where every node points to the next node.
  • Linked List contains a link element called first.
  • Each link carries a data field(s) and a link field called next.
  • Each link is linked with its next link using its next link.
  • The last link carries a link as null to mark the end of the list.

Types of Linked Lists

Singly Linked List: Each node contains data and a pointer to the next node. 

Doubly Linked List: Each node contains data, a pointer to the next node, and a pointer to the previous node. 

Circular Linked List: The last node in the list points back to the first node.

Basic Operations

Following are the basic operations supported by a list.
  1. Insertion − Adds an element at the beginning of the list.
  2. Deletion − Deletes an element at the beginning of the list.
  3. Display − Displays the complete list.
  4. Search − Searches an element using the given key.
  5. Delete − Deletes an element using the given key.

Benefits of Using Linked Lists

Dynamic Size: Linked lists don't have a fixed size, allowing for dynamic resizing.

Efficient Operations: Insertions and deletions are faster compared to arrays, especially if the pointer/reference to the node is already available.

Memory Efficient: Memory is allocated only when required, unlike arrays where the size is fixed in advance.

Drawbacks

Memory Overhead: Each node in a linked list requires extra memory for a pointer/reference to the next node (and the previous node for doubly linked lists), leading to some memory overhead.

Traversal: To access an element, one has to traverse from the head node in most cases, which can be time-consuming.

Linked List Data Structure Implementation in Java

Conclusion

Linked lists provide a dynamic way of storing data and are crucial in the implementation of other advanced data structures like stacks and queues. While they come with certain advantages, understanding their limitations is equally essential to use them effectively. In Java, the built-in LinkedList class also offers various methods for easy manipulations, but having a solid understanding of the core concept is invaluable for budding developers.

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