Implement array-based PositionalList

import java.util.Iterator;

import net.datastructures.*;

public class MyArrayPositionalList implements PositionalList {

@Override

public int size() {

// TODO Auto-generated method stub return 0;

}

@Override public boolean isEmpty() {

// TODO Auto-generated method stub

return false; }

@Override public Position first() {

// TODO Auto-generated method stub

return null; }

@Override public Position last() {

// TODO Auto-generated method stub

return null; }

@Override public Position before(Position p) throws IllegalArgumentException {

// TODO Auto-generated method stub

return null; }

@Override public Position after(Position p) throws IllegalArgumentException {

// TODO Auto-generated method stub

return null; }

@Override public Position addFirst(E e) {

// TODO Auto-generated method stub

return null; }

@Override public Position addLast(E e) {

// TODO Auto-generated method stub

return null; }

@Override public Position addBefore(Position p, E e) throws IllegalArgumentException {

// TODO Auto-generated method stub

return null; }

@Override public Position addAfter(Position p, E e) throws IllegalArgumentException {

// TODO Auto-generated method stub

return null; }

@Override public E set(Position p, E e) throws IllegalArgumentException {

// TODO Auto-generated method stub

return null; }

@Override public E remove(Position p) throws IllegalArgumentException {

// TODO Auto-generated method stub return null;

}

@Override public Iterator> iterator() {

// TODO Auto-generated method stub

return null; }

@Override public Iterable> positions() {

// TODO Auto-generated method stub

return null; }

}

Positional Class

import java.util.Iterator;  public interface PositionalList extends Iterable { /**  * Returns the number of elements in the list.  * @return number of elements in the list  */  int size(); /**  * Tests whether the list is empty.  * @return true if the list is empty, false otherwise  */  boolean isEmpty(); /**  * Returns the first Position in the list.  *  * @return the first Position in the list (or null, if empty)  */  Position first(); /**  * Returns the last Position in the list.  *  * @return the last Position in the list (or null, if empty)  */  Position last(); /**  * Returns the Position immediately before Position p.  * @param p a Position of the list  * @return the Position of the preceding element (or null, if p is first)  * @throws IllegalArgumentException if p is not a valid position for this list  */  Position before(Position p) throws IllegalArgumentException; /**  * Returns the Position immediately after Position p.  * @param p a Position of the list  * @return the Position of the following element (or null, if p is last)  * @throws IllegalArgumentException if p is not a valid position for this list  */  Position after(Position p) throws IllegalArgumentException; /**  * Inserts an element at the front of the list.  *  * @param e the new element  * @return the Position representing the location of the new element  */  Position addFirst(E e); /**  * Inserts an element at the back of the list.  *  * @param e the new element  * @return the Position representing the location of the new element  */  Position addLast(E e); /**  * Inserts an element immediately before the given Position.  *  * @param p the Position before which the insertion takes place  * @param e the new element  * @return the Position representing the location of the new element  * @throws IllegalArgumentException if p is not a valid position for this list  */  Position addBefore(Position p, E e) throws IllegalArgumentException; /**  * Inserts an element immediately after the given Position.  *  * @param p the Position after which the insertion takes place  * @param e the new element  * @return the Position representing the location of the new element  * @throws IllegalArgumentException if p is not a valid position for this list  */  Position addAfter(Position p, E e) throws IllegalArgumentException; /**  * Replaces the element stored at the given Position and returns the replaced element.  *  * @param p the Position of the element to be replaced  * @param e the new element  * @return the replaced element  * @throws IllegalArgumentException if p is not a valid position for this list  */  E set(Position p, E e) throws IllegalArgumentException; /**  * Removes the element stored at the given Position and returns it.  * The given position is invalidated as a result.  *  * @param p the Position of the element to be removed  * @return the removed element  * @throws IllegalArgumentException if p is not a valid position for this list  */  E remove(Position p) throws IllegalArgumentException; /**  * Returns an iterator of the elements stored in the list.  * @return iterator of the list's elements  */  Iterator iterator(); /**  * Returns the positions of the list in iterable form from first to last.  * @return iterable collection of the list's positions  */  Iterable> positions(); }