public class CircularDoublyLinkedList implements List {

private class Node {

private E value;

private Node next, prev;

public Node(E value, Node next, Node prev) {

this.value = value;

this.next = next;

this.prev = prev;

}

public Node(E value) {

this(value, null, null); // Delegate to other constructor

}

public Node() {

this(null, null, null); // Delegate to other constructor

}

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;

}

public void clear() {

value = null;

next = prev = null;

}

} // End of Node class

private class ListIterator implements Iterator {

private Node nextNode;

public ListIterator() {

nextNode = header.getNext();

}

@Override

public boolean hasNext() {

return nextNode != trailer;

}

@Override

public E next() {

if (hasNext()) {

E val = nextNode.getValue();

nextNode = nextNode.getNext();

return val;

}

else

throw new NoSuchElementException();

}

} // End of ListIterator class, DO NOT REMOVE, TEST WILL FAIL

/* private fields */

private Node header, trailer; // "dummy" nodes

private int currentSize;

public CircularDoublyLinkedList() {

/**

* Set dummy nodes to point to each other

*

* --> header trailer

* | |

* __________________________

*

*/

header = new Node();

trailer = new Node(null, header, header);

header.setNext(trailer);

header.setPrev(trailer);

currentSize = 0;

}

@Override

public void add(E obj) {

/*TODO ADD YOUR CODE HERE*/

}

@Override

public void add(E elm, int index) {

/*TODO ADD YOUR CODE HERE*/

}

@Override

public boolean remove(E obj) {

/*TODO ADD YOUR CODE HERE*/

return false;

}

@Override

public boolean remove(int index) {

/*TODO ADD YOUR CODE HERE*/

return false;

}

@Override

public int removeAll(E obj) {

/*TODO ADD YOUR CODE HERE*/

return -1;

}

@Override

public E get(int index) {

/*TODO ADD YOUR CODE HERE*/

return null;

}

@Override

public E set(int index, E newElement) {

/*TODO ADD YOUR CODE HERE*/

return null;

}

@Override

public int firstIndexOf(E obj) {

/*TODO ADD YOUR CODE HERE*/

return -1;

}

@Override

public int lastIndexOf(E obj) {

/*TODO ADD YOUR CODE HERE*/

return -1;

}

@Override

public E first() {

/*TODO ADD YOUR CODE HERE*/

return null;

}

@Override

public E last() {

/*TODO ADD YOUR CODE HERE*/

return null;

}

@Override

public int size() {

/*TODO ADD YOUR CODE HERE*/

return -1;

}

@Override

public boolean isEmpty() {

/*TODO ADD YOUR CODE HERE*/

return false;

}

@Override

public boolean contains(E obj) {

/*TODO ADD YOUR CODE HERE*/

return false;

}

@Override

public void clear() {

/*TODO ADD YOUR CODE HERE*/

}

@Override

public Iterator iterator() {

return new ListIterator();

} //DO NOT DELETE, TESTS WILL FAIL

}

(Fill all TODO)

3. (20 pts) Head over to CircularDoublyLinkedList. java after finishing exercise 2. The instructions for this exercis are as follows: - A circulardoublylinkedList is a linked list where every node has a next pointer and a previous pointer. What going to differentiate this from a regular DoublyLinkediist is that the header and trailer point to each other, making the references at the end of the List circle back to the beginning of the list. - Given the base code, create an implementation of the circularDoublyLinkedList class (with dummy header and trailer) with the knowledge obtained from lectures and previous lab exercises. - Implementations that do not have ALL member methods implemented will receive at most 50% of the credit obtained upon inspection from the professor and/or TAs