$1$ Problem Specification

For this programming assignment, you will be completing the implementation of a java

program for storing the grades of students in a java. util.ArrayList and calculating$/$presenting

some statistics of grades.

To do this, you will complete the implementation of the following classes $($the incomplete

classes are available on Canvas and stored in $"$PA$1$ Draft.zip"$).$

public class Grade: keeps a single grade in the form of both score $($from $0$ to $100)$ and

letter grade $($A$,$ A$-,...,$ F$).$ The assumption is that the letter$-$grade cut$-$off points are

the same as you see in the course syllabus.

public class Student: keeps track of students info: first name $($String$),$ last name

$($String$),7-$digit ID $($int$),$ and grade $($Grade$).$

public class Gradebook: keeps a list of students info in the following data structure:

java. util.ArrayList$($Student$).$

public class Main: contains the main method which does the followings: first it gets

user's input data from

System.in verifies the data to make sure there is no problem

with the input data. Then, it asks for user's commands and gets them via System. in$.$

Finally, it processes each command, and outputs the results to System.out.

Program Input Handling Phase

The program must first ask the user to enter the information of the first student via keyboard

by printing the following message:

Welcome to my grade book!

Please enter the information of the first student using the following format:

"firstName lastName PID grade".

Press Enter when you are done.After user enters the requested information $($e$.$g$.$ "Ann Smith $123456793"),$ the program

must repetitively ask for information of the next student by printing the following message

in a while loop:

Please enter the information of the next student using the same format.

If there is no more students, please enter the keyword "DONE".

Press Enter when you are done.

The user input must meet the following criteria. If any of these criteria are not satisfied,

the program must ask the user to try again:

firstName is a single word which contains alphabetical characters only, starts with a

capital letter and does not include any white space character.

lastName is a single word which contains alphabetical characters only, starts with a

capital letter and does not include any white space character. lastName may contain

at$-$most one $\text{'})$ character too.

PID is a seven digit integer with no leading zeros.

grade is a non$-$negative integer that doesn't exceed $100.$

Program Command Handling Phase

After the user enters the information of all students one$-$by$-$one and enters the keyword

"DONE", your program must keep asking for a new command $($e$.$g$.$ print the message

"Please enter a new command"$)$ and respond to each command properly. Here are the list

of all commands that your program must support:

min score: Your program must calculate and print the minimum score of all students

as the response to this command.

min letter: Your program must calculate and print the minimum letter$-$grade of all

students as the response to this command.

max score: Your program must calculate and print the maximum score of all students

as the response to this command.

max letter: Your program must calculate and print the maximum letter$-$grade of all

students as the response to this command.

letter $xxxxxxx$ : Your program must find and print the letter$-$grade of the student

whose PID is given by the command $($XXXXXXX is the PID where each X representsmax letter: Your program must calculate and print the maximum letter$-$grade of all

students as the response to this command.

letter $xxxxxxx$ : Your program must find and print the letter$-$grade of the student

whose PID is given by the command $($XXXXXXX is the PID where each X represents

a digit$).$

name $xxxxxxx$ : Your program must find and print the full name of the student

whose PID is given by the command $($XXXXXXX is the PID where each X represents

a digit$).$ Full name is made of first name, followed by a single white space and the last

name.

change $xxxxxxxYY$ : Your program must find and update the grade of the student

whose PID is given by the command $($XXXXXXX is the PID where each X represents

a digit$).$ Int this command, $YY$ is the symbol for the new grade.

average score: Your program must calculate and print the average score $($out of $100)$

of all students as the response to this command.

average letter: Your program must calculate and print the letter$-$grade of average score

of all students as the response to this command.

median soore: Your program must calculate and print the median score of all students

as the response to this command.

median letter: Your program must calculate and print the letter$-$grade of median score

of all students as the response to this command.

tab scores: Your program must print the list of all students in the form of a tab$-$

separated table containing four colum