IN JAVA

class ListItem { String data; ListItem next; // To point to next node in list. ListItem prev; // To point to the previous node in the list. } public class DoublyLinkedList4 { // Instance variables. ListItem front = null; ListItem rear = null; int numItems = 0; public void add (String s) { if (front == null) { // Similar to singly-linked list, except for setting rear.prev front = new ListItem (); front.data = s; rear = front; rear.next = null; rear.prev = null; // Must set this correctly. } else { // Make new ListItem and set its fields correctly. ListItem nextOne = new ListItem (); nextOne.data = s; nextOne.next = null; nextOne.prev = rear; // Adjust the next pointer of the current last one, and adjust rear itself. rear.next = nextOne; rear = nextOne; } numItems ++; } public int size () { return numItems; } public String get (int i) { if (i >= numItems) { return null; } int count = 0; ListItem listPtr = front; while (count = numItems) ) { return; } // Find the i-th element. int count = 0; ListItem listPtr = front; while ( (listPtr != null) && (count != i) ) { listPtr = listPtr.next; count ++; } // Otherwise delete: four cases. if (front == rear) { // Case 1: only one element. front = rear = null; } else if (listPtr == front) { // Case 2: we're deleting from the front. front = listPtr.next; front.prev = null; } else if (listPtr == rear) { // Case 3: delete the last element. rear = listPtr.prev; rear.next = null; } else { // Case 4: In the middle: stitch the prev and next nodes together. listPtr.prev.next = listPtr.next; listPtr.next.prev = listPtr.prev; } numItems --; } }

public class DoublyLinkedListExample4 { public static void main (String[] argv) { DoublyLinkedList4 favoriteShows = new DoublyLinkedList4(); favoriteShows.add ("Crocodile Hunter"); favoriteShows.add ("Jon Stewart"); favoriteShows.add ("Evening at the Improv"); favoriteShows.add ("Monty Python"); favoriteShows.add ("SNL"); System.out.println ("Before deletion: "); System.out.println (favoriteShows); favoriteShows.delete ("SNL"); System.out.println ("After deletion:"); System.out.println (favoriteShows); favoriteShows.delete (2); System.out.println ("After deletion:"); System.out.println (favoriteShows); } }