Modify the class LinkedList in Exercise 1 to make it a doubly linked list. Name your class DoublyLinkedList. Add a method addEnd to add an integer at the end of the list and a method displayInReverse to print the list backwards: void addEnd(int x): create this method to add x to the end of the list. void displayInReverse(): create this method to display the list elements from the last item to the first one. Create a main class to test your DoublyLinkedList class.