DeleteNode.java

// Write a function to delete a given node in a doubly linked list.

class LinkedList {   
    static Node head = null;   
    class Node {   
        int data; 
        Node next, prev;   
        Node(int d) { 
            data = d; 
            next = prev = null; 
        } 
    } 
  
    /*Function to delete a node in a Doubly Linked List. 
    head_ref --> pointer to head node pointer. 
    del  -->  pointer to node to be deleted. */
    void deleteNode(Node head_ref, 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; 
    } 
  
    /* Function to insert a node at the beginning of the Doubly Linked List */
    void push(Node head_ref, int new_data) {   
        /* allocate node */
        Node new_node = new Node(new_data);   
        /* since we are adding at the begining, 
         prev is always NULL */
        new_node.prev = null;   
        /* link the old list off the new node */
        new_node.next = (head);   
        /* change prev of head node to new node */
        if ((head) != null) { 
            (head).prev = new_node; 
        }   
        /* move the head to point to the new node */
        (head) = new_node; 
    } 

    void printList(Node node) { 
        while (node != null) { 
            System.out.print(node.data + " "); 
            node = node.next; 
        } 
    } 
  
    public static void main(String[] args) { 
        LinkedList list = new LinkedList();   
        /* Let us create the doubly linked list 10<->8<->4<->2 */
        list.push(head, 2); 
        list.push(head, 4); 
        list.push(head, 8); 
        list.push(head, 10);   
        System.out.println("Original Linked list "); 
        list.printList(head); 
          
        /* delete nodes from the doubly linked list */
        list.deleteNode(head, head);  /*delete first node*/
  
        list.deleteNode(head, head.next);  /*delete middle node*/
  
        list.deleteNode(head, head.next);  /*delete last node*/
        System.out.println(""); 
  
        /* Modified linked list will be NULL<-8->NULL */
        System.out.println("Modified Linked List"); 
        list.printList(head); 
    } 
}