Insertion in Doubly Linked List

   Last Updated: 06 October, 2024       🕓  5 Mins

In this tutorial, we will see all about the insert operation in a doubly linked list. In the insert operation, we will add a new node to the doubly linked list at any position.

In a Doubly Linked List, we can insert a node at the following positions:

1. At the beginning of the list.

2. At the end of the list.

3. At the specific position of the list.

1. Insert a node at the beginning of the list.

In the below given example we will see how to insert a new node in the beginning or front the doubly linked list.

// Java Program to insert a node at the beginning of a doubly linked list public class InsertAtBeginningInDLL { static Node head; // Method to insert a node in doubly linked list static void insertNode(int data) { Node newNode = new Node(data); Node last = head; if (head == null) { head = newNode; return; } while (last.next != null) { last = last.next; } last.next = newNode; newNode.prev = last; } // Method to insert a node at the beginning of the list static Node insertAtBeginning(Node head, int data) { Node new_node = new Node(data); new_node.next = head; // Set previous of head as new node if (head != null) { head.prev = new_node; } return new_node; } // Method to print the doubly linked list public static void printList(Node head) { Node node = head; while (node != null) { System.out.print(node.data + " "); node = node.next; } System.out.println(); } public static void main(String[] args) { // Create a doubly linked list insertNode(10); insertNode(20); insertNode(30); insertNode(40); insertNode(50); System.out.println("Original doubly linked list:"); printList(head); // Insert a new node at the front of the list head = insertAtBeginning(head, 90); // Print the updated list System.out.print("List, After inserting a node at the beginning:\n"); printList(head); } }

Output

  Original doubly linked list:
  10 20 30 40 50 
  List, After inserting a node at the beginning:
  90 10 20 30 40 50

2. Insert a node at the end of the doubly linked list.

In the below given example we will see how to insert a new node at the end of the doubly linked list.

// Java Program to insert a node at the end of doubly linked list public class InsertAtEndInDLL { static Node head; // Method to insert a node in doubly linked list static void insertNode(int data) { Node newNode = new Node(data); Node last = head; if (head == null) { head = newNode; return; } while (last.next != null) { last = last.next; } last.next = newNode; newNode.prev = last; } // Method to insert a new node at the end of the DLL static Node insertNodeAtEnd(Node head, int newData) { Node newNode = new Node(newData); if (head == null) { head = newNode; } else { Node node = head; while (node.next != null) { node = node.next; } // Set the next of last node to the new node node.next = newNode; // Set the prev of new node to the last node newNode.prev = node; } return head; } // Method to print the doubly linked list public static void printList(Node head) { Node node = head; while (node != null) { System.out.print(node.data + " "); node = node.next; } System.out.println(); } public static void main(String[] args) { // Create a doubly linked list insertNode(10); insertNode(20); insertNode(30); insertNode(40); insertNode(50); System.out.println("Original doubly linked list:"); printList(head); // Insert a new node with data 60 at the end head = insertNodeAtEnd(head, 60); System.out.println("After inserting, doubly linked list:"); printList(head); } }

Output

  Original doubly linked list:
  10 20 30 40 50 
  After inserting, doubly linked list:
  10 20 30 40 50 60 

3. Insert a node at a specific position of the list

In the below given example we will see how to insert a new node in the specific position in the doubly linked list.

// Java Program to insert a node at the specific position in DLL public class InsertAtSpecPositionInDLL { static Node head; // Method to insert a node in a doubly linked list static void insertNode(int data) { Node newNode = new Node(data); Node last = head; if (head == null) { head = newNode; return; } while (last.next != null) { last = last.next; } last.next = newNode; newNode.prev = last; } // Method to insert a node at the specific position in a doubly linked list static Node insertNodeAtPosition(Node head, int position, int data) { Node new_node = new Node(data); // Insertion at the beginning if (position == 1) { new_node.next = head; if (head != null) { head.prev = new_node; } head = new_node; return head; } Node curr = head; for (int i = 1; i < position - 1 && curr != null; ++i) { curr = curr.next; } // If the position is out of bounds if (curr == null) { System.out.println("Error: Given position is out of bounds."); return head; } new_node.prev = curr; new_node.next = curr.next; curr.next = new_node; if (new_node.next != null) { new_node.next.prev = new_node; } return head; } // Method to print the doubly linked list public static void printList(Node head) { Node node = head; while (node != null) { System.out.print(node.data + " "); node = node.next; } System.out.println(); } public static void main(String[] args) { // Create a doubly linked list insertNode(10); insertNode(20); insertNode(30); insertNode(40); insertNode(50); System.out.println("Original doubly linked list:"); printList(head); // Insert new node with data 25 at position 3 int data = 25; int position = 3; head = insertNodeAtPosition(head, position, data); System.out.println("After inserting, doubly linked list:"); printList(head); } }

Output

  Original doubly linked list:
  10 20 30 40 50 
  After inserting, doubly linked list:
  10 20 25 30 40 50