Consider the instance variables and constructors.  Given Instance Variables and Constructors: public class SimpleLinkedList implements SimpleList, Iterable, Serializable {      // First Node of the List      private Node first;      // Last Node of the List      private Node last;      // Number of List Elements      private int count;      // Total Number of Modifications (Add and Remove Calls)      private int modCount;        /**       * Creates an empty SimpleLinkedList.       */      publicSimpleLinkedList(){          first = null;          last = null;          count = 0;          modCount = 0;      }      ...   Assume the class contains the following methods that work correctly: public boolean isEmpty() public int size() public boolean add(E e) public E get(int index) private void validateIndex(int index, int end)   Complete the following methods based on the given information from above. /** * Adds an element to the list at the specified position. *  * @param index the position where the element should be added. * @param e the element to be added to the list. * @return true if the list was changed * @throws IndexOutOfBoundsException if the index out of range, i.e. index < 0 or index >= the size(). */ public boolean add(int index, E e) {      // TODO }   /**  * Returns the index of the first occurrence of a given element on the list equal   * or -1 if the given element is not on the list.  If the argument element is null,  * the method returns the index of the first null element on the list, or -1 if the list  * has no null elements.   *   * @param e the element to be located on the list.  * @return the index of the first occurrence of a given element on the list equal or -1   * if the given element is not on the list.  */ public int indexOf(E e) {       // TODO }   /**  * Removes an element from the list at the specified position.  *   * @param index the position where the element should be removed.  * @return the removed element  * @throws IndexOutOfBoundsException if the index out of range, i.e. index < 0 or index >= the size().  */ public E remove(int index) {       // TODO }

Consider the instance variables and constructors. 

Given Instance Variables and Constructors:

public class SimpleLinkedList<E> implements SimpleList<E>, Iterable<E>, Serializable {

     // First Node of the List

     private Node<E> first;

     // Last Node of the List

     private Node<E> last;

     // Number of List Elements

     private int count;

     // Total Number of Modifications (Add and Remove Calls)

     private int modCount;

     /**

      * Creates an empty SimpleLinkedList.

      */

     publicSimpleLinkedList(){

         first = null;

         last = null;

         count = 0;

         modCount = 0;

     }

     ...

Assume the class contains the following methods that work correctly:

public boolean isEmpty()

public int size()

public boolean add(E e)

public E get(int index)

private void validateIndex(int index, int end)

Complete the following methods based on the given information from above.

/**

* Adds an element to the list at the specified position.

* 

* @param index the position where the element should be added.

* @param e the element to be added to the list.

* @return true if the list was changed

* @throws IndexOutOfBoundsException if the index out of range, i.e. index < 0 or index >= the size().

*/

public boolean add(int index, E e) {

     // TODO

}

/**

 * Returns the index of the first occurrence of a given element on the list equal 

 * or -1 if the given element is not on the list.  If the argument element is null,

 * the method returns the index of the first null element on the list, or -1 if the list

 * has no null elements.

  * 

 * @param e the element to be located on the list.

 * @return the index of the first occurrence of a given element on the list equal or -1 

 * if the given element is not on the list.

 */

public int indexOf(E e) {

      // TODO

}

/**

 * Removes an element from the list at the specified position.

 * 

 * @param index the position where the element should be removed.

 * @return the removed element

 * @throws IndexOutOfBoundsException if the index out of range, i.e. index < 0 or index >= the size().

 */

public E remove(int index) {

      // TODO

}