Need the bonus part of this question answered. Code that was done for the previous parts that i did already, are provided down below. Feel free to change anything in my code to answer the question or to fix it. All code in java.

=======================Student.java====================

package student_grade;

@SuppressWarnings("rawtypes")

public class Student implements Comparable {

private String firstName;

private String lastName;

private int pID;

public Student(String aFirst, String aLast, int apID) {

firstName = aFirst;

lastName = aLast;

pID = apID;

}

public int getID() {

return pID;

}

public String getFirst() {

return firstName;

}

public String getLast() {

return lastName;

}

public int compareTo(Object s) {

if (lastName.compareTo(((Student) s).getLast()) != 0)

return lastName.compareTo(((Student) s).getLast());

else if (firstName.compareTo(((Student) s).getFirst()) != 0)

return firstName.compareTo(((Student) s).getFirst());

else

return pID - ((Student) s).getID();

}

}

=====================================Grade.java============================

package student_grade;

public class Grade {

private String letter;

public Grade(String grade) {

letter = grade;

}

public String getLetter() {

return letter;

}

public double getValue() {

switch (letter) {

case "A":

return 4;

case "A-":

return 3.667;

case "B+":

return 3.333;

case "B":

return 3;

case "B-":

return 2.667;

case "C+":

return 2.333;

case "C":

return 2;

case "C-":

return 1.667;

case "F":

return 0;

}

return 0;

}

}

===========================CSVUtil.java===============================

package student_grade;

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.io.FileWriter;

import java.io.IOException;

import java.util.Map;

public class CSVUtil {

private static final String CSV_SPLIT_BY = ",";

public void read(String filename, Map map) {

BufferedReader br = null;

String line = "";

try {

br = new BufferedReader(new FileReader(filename));

while ((line = br.readLine()) != null) {

// use comma as separator

String[] data = line.split(CSV_SPLIT_BY);

Student student = new Student(data[0], data[1], Integer.valueOf(data[2]));

Grade grade = new Grade(data[3]);

map.put(student, grade);

}

}

catch (FileNotFoundException e) {

e.printStackTrace();

}

catch (IOException e) {

e.printStackTrace();

}

finally {

if (br != null) {

try {

br.close();

}

catch (IOException e) {

e.printStackTrace();

}

}

}

}

public void write(String filename, Map map) {

BufferedWriter bw = null;

try {

bw = new BufferedWriter(new FileWriter(filename));

for (Map.Entry itr : map.entrySet()) {

Student student = itr.getKey();

Grade grade = itr.getValue();

bw.write(student.getFirst());

bw.write(CSV_SPLIT_BY);

bw.write(student.getLast());

bw.write(CSV_SPLIT_BY);

bw.write(String.valueOf(student.getID()));

bw.write(CSV_SPLIT_BY);

bw.write(grade.getLetter());

bw.newLine();

}

bw.flush();

}

catch (FileNotFoundException e) {

e.printStackTrace();

}

catch (IOException e) {

e.printStackTrace();

}

finally {

if (bw != null) {

try {

bw.close();

}

catch (IOException e) {

e.printStackTrace();

}

}

}

}

}

===============================GradeBooking.java=================

package student_grade;

public interface GradeBooking {

void csvImport(String filename);

void csvExport(String filename);

void csvExport(String filename, Grade grade);

void addGrade(String firstName, String lastName, int pID, String grade);

Grade findGrade(String firstName, String lastName, int pID);

void removeStudent(String firstName, String lastName, int pID);

double findAverage();

}

==========================HashGradeBook.java==============================

package student_grade;

import java.util.HashMap;

import java.util.Map;

import java.util.NoSuchElementException;

public class HashGradeBook implements GradeBooking {

private Map map;

private CSVUtil csvUtil;

public HashGradeBook() {

map = new HashMap();

csvUtil = new CSVUtil();

}

@Override

public void csvImport(String filename) {

csvUtil.read(filename, map);

}

@Override

public void csvExport(String filename) {

csvUtil.write(filename, map);

}

@Override

public void csvExport(String filename, Grade grade) {

Map filteredStudent = new HashMap();

for (Map.Entry itr : map.entrySet()) {

if (grade.equals(itr.getValue())) {

filteredStudent.put(itr.getKey(), itr.getValue());

}

}

csvUtil.write(filename, filteredStudent);

}

@Override

public void addGrade(String firstName, String lastName, int pID, String grade) {

Student student = new Student(firstName, lastName, pID);

Grade newGrade = new Grade(grade);

map.put(student, newGrade);

}

@Override

public Grade findGrade(String firstName, String lastName, int pID) {

Student student = new Student(firstName, lastName, pID);

if (!checkStudentAvailability(student)) {

throw new NoSuchElementException("Student is not found...");

}

return map.get(student);

}

@Override

public void removeStudent(String firstName, String lastName, int pID) {

Student student = new Student(firstName, lastName, pID);

if (checkStudentAvailability(student)) {

map.remove(student);

}

}

@Override

public double findAverage() {

double average = 0;

if (map.isEmpty()) {

throw new NoSuchElementException("No data available...");

}

for (Map.Entry itr : map.entrySet()) {

average += itr.getValue().getValue();

}

return average;

}

private boolean checkStudentAvailability(Student student) {

for (Map.Entry itr : map.entrySet()) {

if(itr.getKey().compareTo(student)==0){

return true;

}

}

return false;

}

}

=============================TreeGradeBook.java=========================

package student_grade;

import java.util.Map;

import java.util.NoSuchElementException;

import java.util.TreeMap;

public class TreeGradeBook implements GradeBooking {

private Map map;

private CSVUtil csvUtil;

public TreeGradeBook() {

map = new TreeMap();

csvUtil = new CSVUtil();

}

@Override

public void csvImport(String filename) {

csvUtil.read(filename, map);

}

@Override

public void csvExport(String filename) {

csvUtil.write(filename, map);

}

@Override

public void csvExport(String filename, Grade grade) {

Map filteredStudent = new TreeMap();

for (Map.Entry itr : map.entrySet()) {

if (grade.equals(itr.getValue())) {

filteredStudent.put(itr.getKey(), itr.getValue());

}

}

csvUtil.write(filename, filteredStudent);

}

@Override

public void addGrade(String firstName, String lastName, int pID, String grade) {

Student student = new Student(firstName, lastName, pID);

Grade newGrade = new Grade(grade);

map.put(student, newGrade);

}

@Override

public Grade findGrade(String firstName, String lastName, int pID) {

Student student = new Student(firstName, lastName, pID);

if (!map.containsKey(student)) {

throw new NoSuchElementException("Student is not found...");

}

return map.get(student);

}

@Override

public void removeStudent(String firstName, String lastName, int pID) {

Student student = new Student(firstName, lastName, pID);

if (map.containsKey(student)) {

map.remove(student);

}

}

@Override

public double findAverage() {

double average = 0;

if (map.isEmpty()) {

throw new NoSuchElementException("No data available...");

}

for (Map.Entry itr : map.entrySet()) {

average += itr.getValue().getValue();

}

return average;

}

}

==============================StudentGradleHandler.java===========================

package student_grade;

public class StudentGradleHandler {

public static void main(String[] args) {

HashGradeBook book = new HashGradeBook();

book.csvImport("student.csv");

book.csvExport("output.csv");

book.addGrade("Chirs", "Gayle", 222324, "C+");

System.out.println("Grade for Chirs Gayle is: " + book.findGrade("Chirs", "Gayle", 222324));

System.out.println("Average to Hash Grade Book: " + book.findAverage());

}

}