Note: Use the provided ratings.datastructures.LinkedListNode class whenever a linked list is needed. You do not have to

modify this class

ratings.Song $-$ The following methods will be added to the Song class:

A method named addRating that takes a $[$reference to$]$ an object of type Rating as a parameter $($The type of the

input is Rating$)$ and returns void

This method will be called when a Reviewer rates this Song. All added Ratings will be stored in a Linked List as

an instance variable

This method will append new ratings to the end of the linked list

Note: Since the Rating class checks for valid ratings, any added ratings can only have a rating value of $1,2,3,$

$4,5,$ or $-1$

A method named getRatings that takes no parameters and returns a LinkedListNode of Ratings

This method returns the head of a Linked List containing all Ratings that have been added to this Song

The returned Linked List must return the Ratings in the order in which they were added. For example, the first

Rating that was added must be the first value in the list

If no ratings have been added, this method will return null

A method named

that takes a LinkedListNode of Ratings and returns void

This is a setter that replaces the stored linked list of ratings $($The instance variable$)$ with the one provided as a

parameter. This assignment is done by reference $($ie$.$ any prior ratings are replaced by the new list of ratings$)$

A method named averageRating that takes no parameters and returns a double

This method returns the average of all the Ratings of this Song

If the list is empty, the method returns $0\mathrm{.}0$

Any invalid rating, ratings of $-1,$ will be ignored during this calculation $($eg$.$ A Song with ratings $1,5,-1,-1$ has

an average rating of $3\mathrm{.}0)$

A method named

that takes a Reviewer as a parameter and returns void

This method will remove a Rating made for this Song by the given Reviewer by id

If the reviewer did not rate this song, this method has no effect

If the linked list contains multiple ratings by the reviewer, the method only removes the first instance from the

list $($ie$.$ the method does not have to handle removing multiple ratings in a single call$)$