The code that needs to be modified is below. Thank you.

QUESTION: Implement Doubly Linked List add method which add an element to a specific position. - Its an instance method that takes a position and an element, then adds the element to this specific position and shifts the element currently at this position and any subsequent elements to the right. It throws an exception if the position is out of bound. It traverses the list from header if the position is closer to the header and traverses the list from trailer otherwise.

BELOW IS THE DRIVER'S CODE:

public class A1LinkedList{ public static void main(String argc[]){ Linkedlist sl = new Linkedlist<>(); DLinkedList dl = new DLinkedList<>(); PolynomialLinkedlist sum, prod; for (int i = 1000; i > 0; i-=3) sl.add(i); try { sl.insert(111, sl.getNode(50), sl.getNode(51)); if (sl.detectLoop()) System.out.println("Loop!"); else System.out.println("No loop."); sl.insert(123, sl.getNode(51), sl.getNode(50)); if (sl.detectLoop()) System.out.println("Loop!"); else System.out.println("No loop."); } catch(Exception e){ e.printStackTrace(); } dl.add("Three",0); dl.add("Five",1); dl.add("One",0); dl.add("Two",1); dl.add("Four",3); dl.print(); PolynomialLinkedlist p1 = new PolynomialLinkedlist(2,3); PolynomialLinkedlist p2 = new PolynomialLinkedlist(3,2); p3 = p1.add(p2); p1 = new PolynomialLinkedlist(3,2); p2 = new PolynomialLinkedlist(1,0); p4 = p1.add(p2); sum = p3.add(p4); prod = p3.multiply(p4); sum.print(); prod.print(); p1.print(); p2.print(); } } BELOW IS THE LINKLIST CLASS:  class Linkedlist{ private static class Node{ private E element; private Node next; public Node(E e, Node n){ element = e; next = n; } public E getE(){ return element; } public Node getNext(){ return next; } public void setE(E e){ element = e; } public void setNext(Node n){ next = n; } } private Node head; public Linkedlist(){ head = null; } public void add(E e){ Node temp = new Node<>(e, head); head = temp; } public void insert(E e, Node p, Node n){ p.setNext(new Node<>(e, n)); } public Node getNode(int i) throws Exception{ Node temp = head; while (i > 0){ if (temp == null) throw new Exception("Out of bound"); temp = temp.getNext(); i--; } return temp; } } BELOW IS THE CODE WHERE THE ADD METHOD NEEDS TO BE MODIFIED: class DLinkedList{ private static class DNode{ private E element; private DNode prev; private DNode next; public DNode(E e){ this(e, null, null); } public DNode(E e, DNode p, DNode n){ element = e; prev = p; next = n; } public E getE(){ return element; } public DNode getPrev(){ return prev; } public DNode getNext(){ return next; } public void setE(E e){ element = e; } public void setPrev(DNode p){ prev = p; } public void setNext(DNode n){ next = n; } } private DNode header; private DNode trailer; private int size; public DLinkedList(){ header = new DNode(null); trailer = new DNode(null, header, null); header.setNext(trailer); size = 0; } public void print(){ DNode temp = header.getNext(); while (temp != trailer){ System.out.print(temp.getE().toString() + ", "); temp = temp.getNext(); } System.out.println(); }

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