LAB EXERCISE 23: Student Data 1

Goal: In this exercise, you will learn how to:
1. Insert the Main Method (Main Entry Point to the Java Program)
2. Import the Scanner Library Class to accept data from the console
3. Import the Library Classes which allow data to be written to an external text file
a. import java.io.File
b. import java.io.FileWriter
c. import java.io.BufferedWriter
d import java.io.IOException
4. Use the tab delimiter “\t” to separate the data fields(variables) when writing the data to a file.
5. Create a Superclass
6. Create a Subclasses
7. Declare Public Variables that can be accessed by a Subclass
8. Create Public Void Methods
9. Create Public Methods that will return values
10. Use a Try-Catch block statement for error file handling and exceptions
11. Create the Object from the Class
12. Call the Object’s Method

Program Specifications:
The program prompts the user to enter the student ID, first and last name, total Lab exercises points, total Project points and Final Exam points. The program then calculates the student total points earned and the student's letter grade.

The data will be written to an external text file.

In the text file, each line is the student’s data which makes up a single record (row).

The record will contain 6 fields separated by a “tab” delimiter: student ID, student first name, last name, course, total points earned and letter grade

A. Pre-requisites:
1. Create a folder on your desktop Exercise-23

2. Launch Java EE- Eclipse
Note: You will need to use the Java Perspective Workbench for this exercise

3. Setup your Eclipse Workspace to point to the Exercise-23 folder
a. Select File-> Switch Workspace
b. Browse and select your Exercie-23 folder as your Workspace.

B. Requirements:

1. Create a Java Project and name it as StudentDataPart1

2. Create the first Class that will have the Main Method

a. Name the Class as MainApp

b. Choose the main method to insert into the class

3. Create a class called Student. This will be the superclass (parent)

4. Create a class called Grade. This subclass that will inherit the methods and variables of the Student superclass

5. Create a class called Data. This subclass that will inherit the methods and variables of the Grade superclass

C. Requirements for the Student Class:

1. Insert the import java.util.Scanner class which will allow data to be inputted from the console.
Insert the line @SuppressWarnings("resource")

2. Create the public variables

public String id, lastName, firstName, letterGrade;
public int labPoints, projectPoints, finaExamPoints, totalPoints;

3. Create the public constant static variables and initialize

public final static String COURSE= "COMSC-051 Java Programming Part 1";
public final static String COLLEGE= "Los Medanos College";

4. Create the public Void Method called getData() that will prompt the user to input the data. Below is the code for the method.

// declare the scanner object used to input the student's ID from the console
Scanner inputID= new Scanner(System.in);
System.out.print("Enter the Student ID: ");
id = inputID.nextLine();

// declare the scanner object used to input the student's last name from the console
Scanner inputLastName= new Scanner(System.in);
System.out.print("Enter the Last Name: ");
lastName = inputLastName.nextLine();

// declare the scanner object used to input the student's first name from the console
Scanner inputFirstName= new Scanner(System.in);
System.out.print("Enter the First Name: ");
firstName = inputFirstName.nextLine();

// declare the scanner object used to input the lab exercises points earned from the console
Scanner inputLabPoints= new Scanner(System.in);
System.out.print("Enter the Total Points for Lab Exerices (Max Points: 750): ");
labPoints = inputLabPoints.nextInt();

// declare the scanner object used to input the project points earned from the console
Scanner inputProjectPoints= new Scanner(System.in);
System.out.print("Enter the Points for Projects: (Max Points: 150):");
projectPoints = inputProjectPoints.nextInt();

// declare the scanner object used to input the final exam points earned from the console
Scanner inputFinalExam= new Scanner(System.in);
System.out.print("Enter the Points for Final Exam: (Max Points: 100): ");
finaExamPoints = inputFinalExam.nextInt();

D. Requirements for the Grade Class:

1. The Grade class will be a subclass of the Student parent class (superclass)
NOTE: A subclass will inherit the methods and variables from the superclass

Add the keyword "extends Students" after the name of class

2. Create the a public Method called calcTotalPoints () with an integer returned data type that will calculate the total points earned by the student

totalPoints = labPoints + projectPoints + finaExamPoints;
return totalPoints;

3. Create the a public Method called calcGrade() with a String returned data type that will calculate the student’s letter grade based on the total points earned

if (totalPoints>=900) {
return letterGrade="A";
} else if(totalPoints >=800 && totalPoints <900) {
return letterGrade="B";
} else if (totalPoints >=700 && totalPoints <800) {
return letterGrade="C";
} else if (totalPoints >=600 && totalPoints<700){
return letterGrade="D";
} else {
return letterGrade="F";
}

4. Create the public Void Method called displayData() that will display the required output on the screen. Below is the code for the method.

// display the inputed data on the console
System.out.println();
System.out.println("Student ID: " + id);
System.out.println("Student Name: " + firstName + " " + lastName);
System.out.println("College: " + COLLEGE);
System.out.println("Course: " + COURSE);

// display the returned results on the console
System.out.println("Total Points: " + totalPoints);
System.out.println("Course Grade: " + letterGrade);

E. Requirements for the Data Class:

1. The Data class will be a subclass of the Student parent class (superclass)
NOTE: A subclass will inherit the methods and variables from the superclass
Add the keyword "extends Grade" after the name of class

2. Insert the following Library Classes which will write and store the data to an external text file
import java.io.File;
import java.io.FileWriter;
import java.io.BufferedWriter;
import java.io.IOException;

3. Insert the import java.util.Scanner class which will allow data to be inputted from the console.

4. Create a Void Method called writeData () that will execute the code to write the data to an external file – studentdata.txt
a. Declare the scanner object used to input the number of students in the class

Scanner inputNum= new Scanner(System.in);
System.out.print("Enter the number of students in the class: ");
int numStudents = inputNum.nextInt(); // assign the input value to the variable
System.out.println();

b. Create instance of the object filename from the File library class & pass the file name “studentdata.txt” as a parameter

File filename = new File("studentdata.txt");

c. Use Try-Catch block to perform error handling if the program cannot write to the external file
b1. Create the instance of the object "fw" from the FileWriter library class
& pass value of "filename" object as the parameter

FileWriter fw = new FileWriter(filename);

b2. Create instance of the object "br" from the BufferredWriter library class & pass the value of the "fw" object as the parameter

BufferedWriter bw = new BufferedWriter(fw);

b3. Create a For loop to perform the iteration of the code based on the number of students in the class.
i. Call the methods from the parent class

getData(); // call the void method from the parent class- StudentGrade
totalPoints = calcTotalPoints(); // call the method from the parent class and store the return results into the variable
letterGrade = calcGrade(); // call the method from the parent class and store the return results into the variable
displayData(); // call the void method from the parent class- StudentGrad

ii. Write the data to the studentdata.txt file using "bw" object write method
Insert tabs “\t” as the tab delimiter between the data fields (variables)

bw.write(id +"\t"+lastName+"\t"+firstName + "\t"+ COURSE + "\t"+ totalPoints + "\t" + letterGrade );
bw.newLine();

iii. Display the message that data was written successfully to external file

System.out.println();
System.out.println("Data has been saved to studentdata.txt file");
System.out.println();

d. Close the BufferedWriter object

bw.close(); // close the BufferedWriter object

e. In the Catch-block parameter, add (IOException e)
Insert the code below to display the error handling message if cannot write to file

System.out.println("Unable to write to the file: " + filename.toString());

f. Close the Scanner object

inputNum.close(); // close the Scanner object

F. Requirements for the MainApp Class:

1. Add comments (documentation)– Program Description, Author and Date

2. Create an instance of the object - employeeInfo from the Data class:
Data studentInfo = new Data()

3. Call the object's void method- writeData:
studentInfo.writeData();

G. Test:

1. Save your Java code

2. Compile and run your Java program.

3. Verify there is no syntax, logical or run-time errors.

4. Use the following set of test data to determine if the application is running properly

5. Expand the Project Folder. Press F5 to Refresh. Verify the studentdata.txt is in the root of the project folder.

H. Submit your exercise in the Canvas Lab Exercise #23 Drop Box.

1. Submit the screen shot of the Eclipse Workbench window showing the Console output screen.
You can use Paint (save as JPG) or Word to paste the screenshot.

2. Submit the studentdata.txt data file.

3. Zip up and submit the compressed StudentDataPart1 subfolder that is in the Exercise-23 folder.
NOTE: Right click on the subfolder and select Send to “Compress Folder”. The file will have a file extension of .zip.

NOTE: You will need to upload the 3 files above separately.