Java Program For Deleting A Node In A Doubly Linked List

// Java program to delete a node from
// Doubly Linked List

// Class for Doubly Linked List
public class DLL 
{
    // Head of list
    Node head; 

    // Doubly Linked list Node
    class Node 
    {
        int data;
        Node prev;
        Node next;

        // Constructor to create a new 
        // node. next and prev is by 
        // default initialized as null
        Node(int d) { data = d; }
    }

    // Adding a node at the front of 
    // the list
    public void push(int new_data)
    {
        // 1. Allocate node
        // 2. Put in the data
        Node new_Node = new Node(new_data);

        // 3. Make next of new node as head
        //    and previous as NULL
        new_Node.next = head;
        new_Node.prev = null;

        // 4. Change prev of head node to 
        //    new node
        if (head != null)
            head.prev = new_Node;

        // 5. Move the head to point to the 
        //    new node
        head = new_Node;
    }

    // This function prints contents of 
    // linked list starting from the given node
    public void printlist(Node node)
    {
        Node last = null;

        while (node != null) 
        {
            System.out.print(node.data + " ");
            last = node;
            node = node.next;
        }

        System.out.println();
    }

    // Function to delete a node in a Doubly 
    // Linked List. head_ref --> pointer to 
    // head node pointer. del --> data of node 
    // to be deleted.
    void deleteNode(Node del)
    {
        // Base case
        if (head == null || del == null) 
        {
            return;
        }

        // If node to be deleted is head node
        if (head == del) 
        {
            head = del.next;
        }

        // Change next only if node to be 
        // deleted is NOT the last node
        if (del.next != null) 
        {
            del.next.prev = del.prev;
        }

        // Change prev only if node to be 
        // deleted is NOT the first node
        if (del.prev != null) 
        {
            del.prev.next = del.next;
        }

        // Finally, free the memory occupied 
        // by del
        return;
    }

    // Driver Code
    public static void main(String[] args)
    {
        // Start with the empty list
        DLL dll = new DLL();

        // Insert 2. So linked list becomes 
        // 2->NULL
        dll.push(2);

        // Insert 4. So linked list becomes 
        // 4->2->NULL
        dll.push(4);

        // Insert 8. So linked list becomes 
        // 8->4->2->NULL
        dll.push(8);

        // Insert 10. So linked list becomes 
        // 10->8->4->2->NULL
        dll.push(10);

        System.out.print("Created DLL is: ");
        dll.printlist(dll.head);

        // Deleting first node
        dll.deleteNode(dll.head);

        // List after deleting first node
        // 8->4->2
        System.out.print(
        "List after deleting first node: ");
        dll.printlist(dll.head);

        // Deleting middle node from 8->4->2
        dll.deleteNode(dll.head.next);

        System.out.print(
        "List after Deleting middle node: ");
        dll.printlist(dll.head);
    }
}