Instruction: Consider a member method of the List ADT named isPalindrome. This method determines whether the elements in the list form a palindrome. That is, whether you get tne same result if you read the elements moving forward as moving backwards. If the current list is empty, it should return true. Implement this method for the DoublyLinkedList class. The following lists examples of palindromes: {}, {Ken}, {Ken, Ken}, {Ken, Bob, Ken}, {Ken, Bob, Bob, Ken}, {Ken, Bob, Ron, Bob, Ken}, {1, 3, 5, 7, 5, 3, 1}. This doubly linked list has a dummy header and a dummy trailer.

import java.util.Iterator; import java.util.NoSuchElementException; public class DoublyLinkedListWrapper { public static interface List extends Iterable { public int size(); public boolean isEmpty(); public boolean isMember(E e); public int firstIndexOf(E e); public int lastIndexOf(E e); public void add(E e); public void add(E e, int index); public E get(int index); public E remove(int index); public boolean remove(E e); public int removeAll(E e); public E replace(int index, E newElement); public void clear(); public Object[] toArray(); public boolean isPalindrome(); } public static class DoublyLinkedList implements List { @SuppressWarnings("hiding") private class DoublyLinkedListIterator implements Iterator{ private Node nextNode; @SuppressWarnings("unchecked") public DoublyLinkedListIterator() { this.nextNode = (Node) header.getNext(); } @Override public boolean hasNext() { return nextNode != trailer; } @Override public E next() { if (this.hasNext()) { E result = this.nextNode.getValue(); this.nextNode = this.nextNode.getNext(); return result; } else { throw new NoSuchElementException(); } } } private static class Node { private E value; private Node next, prev; public Node(E value, Node next, Node prev) { super(); this.value = value; this.next = next; this.prev = prev; } public Node() { this(null, null, null); } public E getValue() { return value; } public void setValue(E value) { this.value = value; } public Node getNext() { return next; } public void setNext(Node next) { this.next = next; } public Node getPrev() { return prev; } public void setPrev(Node prev) { this.prev = prev; } } private Node header, trailer; private int currentSize; public DoublyLinkedList() { this.header = new Node<>(); this.trailer = new Node<>(null, null, header); header.setNext(trailer); this.currentSize = 0; } @Override public int size() { return this.currentSize; } @Override public boolean isEmpty() { return this.size() == 0; } @Override public boolean isMember(E e) { return this.firstIndexOf(e) >= 0; } @Override public int firstIndexOf(E e) { int i = 0; for (Node temp = this.header.getNext(); temp != null; temp = temp.getNext(), ++i) { if (temp.getValue().equals(e)) { return i; } } // not found return -1; } @Override public void add(E e) { Node newNode = new Node(e, trailer, trailer.getPrev()); trailer.getPrev().setNext(newNode); trailer.setPrev(newNode); currentSize++; } @Override public void add(E e, int index) { if ((index < 0) || (index > this.currentSize)) { throw new IndexOutOfBoundsException(); } if (index == this.currentSize) { this.add(e); } else { Node temp = null; if (index == 0) { temp = this.header; } else { temp = this.getPosition(index -1); } Node newNode = new Node<>(e, temp.getNext(), temp); temp.getNext().setPrev(newNode); temp.setNext(newNode); this.currentSize++; } } @Override public E get(int position) { if ((position < 0) || position >= this.currentSize) { throw new IndexOutOfBoundsException(); } Node temp = this.getPosition(position); return temp.getValue(); } private Node getPosition(int index){ int currentPosition=0; Node temp = this.header.getNext(); while(currentPosition != index) { temp = temp.getNext(); currentPosition++; } return temp; } @Override public E remove(int index) { if ((index < 0) || (index >= this.currentSize)){ throw new IndexOutOfBoundsException(); } else { Node curNode = this.header.getNext(); for (int pos = 0; pos < index; pos++) curNode = curNode.getNext(); E result = curNode.getValue(); curNode.getPrev().setNext(curNode.getNext()); curNode.getNext().setPrev(curNode.getPrev()); curNode.setValue(null); curNode.setNext(null); curNode.setPrev(null); this.currentSize--; return result; } } @Override public E replace(int position, E newValue) { if ((position < 0) || position >= this.currentSize) { throw new IndexOutOfBoundsException(); } Node temp = this.getPosition(position); E result = temp.getValue(); temp.setValue(newValue); return result; } @Override public void clear() { while(!this.isEmpty()) { this.remove(0); } } @Override public Object[] toArray() { Object[] result = new Object[this.size()]; for (int i=0; i < this.size(); ++i) { result[i] = this.get(i); } return result; } @Override public Iterator iterator() { return new DoublyLinkedListIterator(); } @Override public int lastIndexOf(E e) { int i = 0; for (Node temp = this.header.getNext(); temp != null; temp = temp.getNext(), ++i) { if (temp.getValue().equals(e)) { return i; } } // not found return -1; } @Override public boolean remove(E e) { int i = this.firstIndexOf(e); if (i < 0) { return false; }else { this.remove(i); return true; } } @Override public int removeAll(E e) { int count = 0; while (this.remove(e)) { count++; } return count; } @Override public boolean isPalindrome() { // ADD YOUR CODE HERE } } }