PLEASE IMPLEMENT BELOW REVERSE DOUBLE LINKED LIST METHOD USING GENERIC FUNCTION.

Question

PLEASE IMPLEMENT BELOW REVERSE DOUBLE LINKED LIST METHOD USING GENERIC FUNCTION.

public class ReverseDoublyLinkedList {

static Node head;

static class Node {

int data;
Node next, prev;

Node(int d) {
data = d;
next = prev = null;
}
}

/* Function to reverse a Doubly Linked List */
void reverse() {
Node temp = null;
Node current = head;

/* swap next and prev for all nodes of
doubly linked list */
while (current != null) {
temp = current.prev;
current.prev = current.next;
current.next = temp;
current = current.prev;
}

/* Before changing head, check for the cases like empty
list and list with only one node */
if (temp != null) {
head = temp.prev;
}
}

/* UTILITY FUNCTIONS */
/* Function to insert a node at the beginging of the Doubly Linked List */
void push(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;
}

/* Function to print nodes in a given doubly linked list
This function is same as printList() of singly linked lsit */
void printList(Node node) {
while (node != null) {
System.out.print(node.data + " ");
node = node.next;
}
}

public static void main(String[] args) {
ReverseDoublyLinkedList list = new ReverseDoublyLinkedList();

/* Let us create a sorted linked list to test the functions
Created linked list will be 6->5->9->10->8->4->2 */
list.push(2);
list.push(4);
list.push(8);
list.push(10);
list.push(9);
list.push(5);
list.push(6);
System.out.println("Original linked list ");
list.printList(head);

list.reverse();
System.out.println("");
System.out.println("The reversed Linked List is ");
list.printList(head);
}
}

Explanation / Answer

Below is your class with Generics. I have added Double and int two implementations to demonstrate the generics . Let me know if you have any issue: -

ReverseDoublyLinkedList.java

public class ReverseDoublyLinkedList<T> {

static Node head;

static class Node<T> {

T data;

Node<T> next, prev;

Node(T d) {

data = d;

next = prev = null;

}

}

/* Function to reverse a Doubly Linked List */

void reverse() {

Node<T> temp = null;

Node<T> current = head;

/*

* swap next and prev for all nodes of doubly linked list

*/

while (current != null) {

temp = current.prev;

current.prev = current.next;

current.next = temp;

current = current.prev;

}

/*

* Before changing head, check for the cases like empty list and list

* with only one node

*/

if (temp != null) {

head = temp.prev;

}

}

/* UTILITY FUNCTIONS */

/* Function to insert a node at the beginging of the Doubly Linked List */

void push(T new_data) {

/* allocate node */

Node<T> new_node = new Node<T>(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;

}

/*

* Function to print nodes in a given doubly linked list This function is

* same as printList() of singly linked lsit

*/

void printList(Node<T> node) {

while (node != null) {

System.out.print(node.data + " ");

node = node.next;

}

}

public static void main(String[] args) {

ReverseDoublyLinkedList<Integer> list = new ReverseDoublyLinkedList<>();

/*

* Let us create a sorted linked list to test the functions Created

* linked list will be 6->5->9->10->8->4->2

*/

list.push(2);

list.push(4);

list.push(8);

list.push(10);

list.push(9);

list.push(5);

list.push(6);

System.out.println("Original linked list ");

list.printList(head);

list.reverse();

System.out.println("");

System.out.println("The reversed Linked List is ");

list.printList(head);

//Setting head to null to create new list

head = null;

System.out.println(" ------------------List 2 ------------------");

ReverseDoublyLinkedList<Double> list1 = new ReverseDoublyLinkedList<>();

/*

* Let us create a sorted linked list to test the functions Created

* linked list will be 6->5->9->10->8->4->2

*/

list1.push(2.2);

list1.push(4.4);

list1.push(8.3);

list1.push(10.2);

list1.push(9.1);

list1.push(5.8);

list1.push(6.6);

System.out.println("Original linked list ");

list1.printList(head);

list.reverse();

System.out.println("");

System.out.println("The reversed Linked List is ");

list.printList(head);

}

}

Sample Run:-

Original linked list
6 5 9 10 8 4 2
The reversed Linked List is
2 4 8 10 9 5 6
------------------List 2 ------------------
Original linked list
6.6 5.8 9.1 10.2 8.3 4.4 2.2
The reversed Linked List is
2.2 4.4 8.3 10.2 9.1 5.8 6.6

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