task: modify this program to implement a Circular Doubly Linked List.

class Node { /////// Implementation of Doubly Linked List public int info; public String name; public double cgpa; public Node next; public Node previous; public Node() { } public Node(int i, String nm, double g) { info = i; name=nm; cgpa=g; } } ////////////////////////////////////////////// class myDLL { protected Node head, tail; public myDLL() { head = tail = null; } public boolean isEmpty() { return head == null; } public void addToHead(int el, String nm, double g) { Node newNode = new Node(el, nm, g); if (head == null) // empty tail = head = newNode; else { newNode.next = head; head = newNode; newNode.previous = null; } } //////////////////////////////////// public void addToTail(int el, String nm, double g) { Node newNode = new Node(el, nm, g); newNode.next = null; if (head == null) // empty head = tail = newNode; else { newNode.previous = tail; tail.next = newNode; tail = newNode; } } //////////////////////////////////// public boolean addBefore(int el, String nm, double g, int target) { if (head.info == target) { //target is 1st node, add before it Node newNode = new Node(el, nm, g); newNode.next = head; head = newNode; newNode.previous = null; } else { // find the predecessor of target Node tmp = head; while (tmp.next != null && tmp.next.info != target) tmp = tmp.next; // check next node if (tmp.next == null) { // not present System.out.println("Target not found"); return false; } else { //tmp is before target Node newNode = new Node(el, nm, g); newNode.next = tmp.next; (tmp.next).previous = newNode; newNode.previous = tmp; tmp.next = newNode; } } return true; } //////////////////////////////////// public int deleteFromHead() { // delete head and return info; if(head == null) // empty return -1; int el = head.info; if (head == tail) // if only one node on the list; head = tail = null; else { head = head.next; head.previous = null; } return el; } //////////////////////////////////// public int deleteFromTail() { // delete tail and return info; if(head == null) // empty return -1; int el = tail.info; if (head == tail) // if only one node on the list; head = tail = null; else { // if many nodes, find predecessor of tail Node tmp = head; while (tmp.next != tail) tmp = tmp.next; tail = tmp; // predecessor of tail becomes tail tail.next = null; } return el; } //////////////////////////////////// public boolean delete(int el) { // delete target node with el; if (head == null) //empty return false; if (head == tail && el == head.info) // one node, target head = tail = null; else if (el == head.info){ // if more nodes, target is head head = head.next; head.previous = null; } else { // if many nodes in the list, el not head Node prev = head, tmp = head.next; while ( tmp != null && tmp.info != el) { prev = prev.next; tmp = tmp.next; } if (tmp != null) { // if el was found; prev.next = tmp.next; (tmp.next).previous = prev; if (tmp == tail) { // if el is in last node; tail = prev; tail.next = null; } } else return false; } return true; } //////////////////////////////////// public void printAll() { System.out.print("null"); for (Node tmp = head; tmp != null; tmp = tmp.next) System.out.print(" <- " + tmp.info + " " + tmp.name + " "+ tmp.cgpa + " -> "); System.out.println("null"); } //////////////////////////////////// public void printAllReverse() { // print in reverse System.out.print("null"); for (Node tmp = tail; tmp != null; tmp = tmp.previous) System.out.print(" <- " + tmp.info + " " + tmp.name + " "+ tmp.cgpa + " -> "); System.out.println("null"); } /////////////////////////////////// public boolean isInList(int el) { Node tmp = head; while (tmp != null && tmp.info != el) tmp = tmp.next; return tmp != null; } //////////////////////////////////// } /////////////////////////////////////////////// public class DoublyLinkedList { public static void main(String[] args) { myDLL L1 = new myDLL(); System.out.println("Empty ? " + L1.isEmpty()); L1.addToTail(2019, "Zain", 2.50); L1.addToHead(2020, "Ahmed", 2.75); L1.addToTail(2022, "Majid", 2.95); L1.addToHead(2021, "Khalid", 2.90); L1.printAll(); int x=2020; System.out.println("Found "+ x + " " + L1.isInList(x)); System.out.println("addBefore " + x); L1.addBefore(2023, "Hamid", 2.00, x); L1.printAll(); System.out.println("Delete from tail"); L1.deleteFromTail(); L1.printAll(); System.out.println("Delete " + x); L1.delete(x); L1.printAll(); System.out.println("Print in Reverse "); L1.printAllReverse(); } }