Project#1: Grade Book

Transcription

1 Project#1: Grade Book Objective Making Classes and Objects from these Classes. Also, practice making an array of objects and manipulating/using the data inside said array. Program Description This program is a basic grade book. The user will first enter the course number and instructor name (first and last name) of some course. Next, the user will enter the total number of students in the course (see output example). You will then make an array of student object references, and you will use this user input (number of students in the course) to make the correct size of the array. Then, the program will display the following menu to the user: For this program, you will create a Class called Student. This class, Student, will be used to create objects of type Student. Each Student object will store all the needed information for one student. So instead of using five different arrays, you will use only one array, an array of Student objects. As an example, if you want your array variable to be called students, you can declare and create your array as follows: Student[] students = new Student[numStudents]; - numstudents is the number of students input by the user What does this line do? It creates an array of references. Note: each reference has a default value of null. Until now, we have NOT created any objects. Student objects are only created when we the user Adds a student record. At that time, a new Student object will be created and the reference for that object will be saved in the appropriate location of the array.

2 Menu Choices: 1. Add a new student record If the user selects choice 1, you should make a new student object, and you will save the reference of this object inside the appropriate index of the student array. The user will then enter the student ID # and the student s first and last name. After this, the user will enter three exam grades as integers. All of this information should be stored inside the newly created student object. So, once the first student is added, that student s information (ID, name,exam grades, etc) can be found inside the Student object at index 0 of the Student object array. The information for the next student will be found at index 1 of the student object array, and so on. Finally, the final grade and letter grade of the student will be calculated and saved into the Student object, and a message is printed to the user. The final grade is calculated as follows: Exam1 is worth 30%, Exam 2 is worth 30%, and the Final Exam is worth 40%. Example: Enter the student's ID and then name (ex: 1587 Ahmad Ashaikh): 111 Ahmed AlGhamdi Enter the student's exam grades: The final grade for Ahmed AlGhamdi(ID# 111) is (A). **So the final grade of was calculated by: 90*(0.3) + 80*(0.3) + 100*(0.4) 2. Search for a student record (by ID) If the user selects choice 2, they will be asked to enter the ID of the student whose record they want to see. If the record is found, it is displayed/printed to the screen. If it is not found, an error message should be displayed. For example: Enter Your Choice: 2 Enter the ID of the student record you want to display: 111 Student Record for Muhammad AlGhamdi (ID # 111): Exam 2: 85 Final Exam: 94 Final Grade: Letter Grade: A Or if not found the output should be like this: Enter the ID of the student record you want to display: 111 ERROR: there is no record for student ID # 111.

3 3. Search for a student record (by first and last name) If the user selects choice 3, they will be asked to enter the first and last name of the student whose record they want to see. If the record is found, it is displayed/printed to the screen. If it is not found, an error message should be displayed. Enter Your Choice: 3 Enter the first and last name of the student you want to display (ex: Ahmad Ashaikh): Muhammad AlGhamdi Student Record for Muhammad AlGhamdi (ID # 111): Exam 2: 85 Final Exam: 94 Final Grade: Letter Grade: A 4. Display statistical results of the class If the user selects choice 4, the statistical results of the class should be displayed/printed to the screen. For example: Enter Your Choice: 4 Statistical Results of ECOM-2324 (Instructor: Daniel Liang): Total number of student records: 3 Average Score: Highest Score: Lowest Score: Total 'A' Grades: 1 (33.33% of class) Total 'B' Grades: 1 (33.33% of class) Total 'C' Grades: 0 (0.00% of class) Total 'D' Grades: 1 (33.33% of class) Total 'F' Grades: 0 (0.00% of class) 5. Display all students If the user selects choice 5, all students, and their details, should print to the screen. For example: Enter Your Choice: 5 ***Class Roster and Grade Sheet*** - Student Record for Muhammad AlGhamdi (ID # 111): Exam 2: 85 Final Exam: 94 Final Grade: Letter Grade: A

4 - Student Record for Abdurrahman Batawi (ID # 871): Exam 2: 70 Final Exam: 82 Final Grade: Letter Grade: B - Student Record for Faisal AlJifri (ID # 253): Exam 1: 40 Exam 2: 80 Final Exam: 60 Final Grade: Letter Grade: D 6. Quit If the user selects choice 6, the program should print a message and then quit. *Note: If any other choice is made, the program should inform the user that the choice is invalid and ask them to try again without quitting the program. Example: Enter Your Choice: 6 Thank you for using the KAU Grade Book. Goodbye. and for invalid choice the output will be: Enter Your Choice: 0 Invalid Choice: please try again. Array Required in Your Program Your program should have ONLY ONE array. This array MUST BE an array of Student objects. You will save all information, for each student, in one Student object. * Of course, inside the Student object, you have a small array (length 3) to store the three exam grades.

5 Description of the two Java Files Needed Here is the UML diagram for the Student Class (Student.java) *All members of the Student class must be private. As a result, you must use accessor and mutator methods (get and set) methods to access and change/set the values. ** Pay close attention to the getexamgrades() and the setexamgrades() methods. For the getexamgrade() method, you send one parameter, the index of the exam you want to get. For the setexamgrades() method, you send two parameters: the grade of the exam and the index where you want to set it. The other Java file is your main program (Gradebook.java ) In addition to the main method, the following methods must be used in your program file: 1. public static void showmenu() The menu gets printed/displayed on the screen. 2. public static double addrecord(parameters here) Inside this method, you must: 1. Ask the user to enter the student ID and name 2. Scan and save the ID and name 3. Ask the user to enter the three exam grades

6 4. Scan and save the three exams 5. create a new student with the given data and add it to the last index of the array of students. 3. public static void searchstudents (parameters here) Inside this method, you must: 1. Ask the user to enter the ID of the student record they want to display 2. Search for this student ID 3. If the student ID is not found, an error message should be printet 4. If the student ID is found, the student s record should be printed 4. public static void searchstudents2 (parameters here) Inside this method, you must: 1. Ask the user to enter the first and last name of the student record they want to display 2. Search for this student first and last name 3. If the student is not found, an error message should be printed 4. If the student is found, the student s record should be printed 5. public static void displayclassstatistics(parameters here) Inside this method, you must: 1. Display the statistical results for the class as given in the example before. 6. public static void displayallstudents (parameters here) Inside this method, you must: 1. Display the record of all students, along with their grades. 2. If there is no student, an error message should be printed Output Format Your program should output in a similar format to the samples given before NOTE: your name, ID, section number should be included as comments in all files! Hint: Getting and setting the exam grades may be tricky at first. So here is a bit of code from the addrecord() method: System.out.print("Enter the student's exam grades): "); for (int i = 0; i < 3; i++) { students[studentcount].setexamgrades(input.nextint(), i); }

7 So as you can see, we are saving the three exam grades into the examgrades array. How are we doing this? We invoke the setexamgrades() method with two parameters: 1. The first parameter is the grade received from the keyboard/input 2. The second parameter is a counter variable, i. So when i is zero, this means that the inputted exam grade will be set at index zero of the examgrades array. When i is 1, the inputted exam grade will be set at index 1 and so on.