Question

Could you implement a gpa calculator so that it asks for a letter grade for each of four classes, calculates the gpa, and prints the GPA out along with the student id, major, and name.

/*****************************Student.java*************************/

public class Student {

   // private data members
   private String id;
   private String name;
   private String major;
   private double gpa;

   // default constructor which set the data member to defualt value
   public Student() {

       this.id = "";
       this.name = "";
       this.major = "";
       this.gpa = 0;
   }

   // parameterized constructor
   public Student(String id, String name, String major, double gpa) {
       this.id = id;
       this.name = name;
       this.major = major;
       this.gpa = gpa;
   }

   // getter and setter
   public String getId() {
       return id;
   }

   public void setId(String id) {
       this.id = id;
   }

   public String getName() {
       return name;
   }

   public void setName(String name) {
       this.name = name;
   }

   public String getMajor() {
       return major;
   }

   public void setMajor(String major) {
       this.major = major;
   }

   public double getGpa() {
       return gpa;
   }

   public void setGpa(double gpa) {
       this.gpa = gpa;
   }

   // print student data
   public void printStudent() {

       System.out.println("Student ID: " + id);
       System.out.println("Student name: " + name);
       System.out.println("Student major: " + major);
       System.out.println("Student GPA: " + gpa);
   }

}

/**************************StudentApplication.java*******************/

public class StudentApplication {

   public static void main(String[] args) {
      
       //create object by default constructor
       Student s1 = new Student();
       //create object by overloaded constructor
       Student s2 = new Student("S12345", "Virat Kohli", "Computer Science", 4.5);
       //set the information of object 1
       s1.setName("John Doe");
       s1.setId("S123456");
       s1.setMajor("Electronics");
       s1.setGpa(4.0);
      
       s1.printStudent();
       System.out.println();
       s2.printStudent();
   }
}

Answer 1

/*
* The java test program that create an instance of Student class and calls the method readClassGrades that prompts
* user to enter 4 credit hours and grade value and then print the student details with the gpa value
* */
//StudentApplication.java
public class StudentApplication
{
   public static void main(String[] args)
   {
       //create object by overloaded constructor
       Student s1 = new Student("S12345", "Virat Kohli", "Computer Science");

       //Call readClassGrades that prompts user to enter the grade and credit hours
       //from user
       s1.readClassGrades();
  
       s1.printStudent();
   }
}

----------------------------------------------------------------------------------------------------------------

//Student.java
import java.util.Scanner;
public class Student
{
   // private data members
   private String id;
   private String name;
   private String major;
   private double gpa;
   // default constructor which set the data member to defualt value
   public Student()
   {
       this.id = "";
       this.name = "";
       this.major = "";
       this.gpa = 0;
   }
   // parameterized constructor
   public Student(String id, String name, String major)
   {
       this.id = id;
       this.name = name;
       this.major = major;
       this.gpa = 0;
   }
  
   /*Read scores */
   public void readClassGrades()
   {
       int course1CreditHours;
       char course1Grade;
       int course2CreditHours;
       char course2Grade;
       int course3CreditHours;
       char course3Grade;
       int course4CreditHours;
       char course4Grade;
      
       //create a Scanner class object
       Scanner console=new Scanner(System.in);
      
       System.out.printf("Enter credit hours course1:");
       course1CreditHours=Integer.parseInt(console.nextLine());
       System.out.printf("Enter course1 Grade :");
       course1Grade=console.nextLine().charAt(0);
      
       System.out.printf("Enter credit hours course2:");
       course2CreditHours=Integer.parseInt(console.nextLine());
       System.out.printf("Enter course2 Grade :");
       course2Grade=console.nextLine().charAt(0);
      
       System.out.printf("Enter credit hours course3:");
       course3CreditHours=Integer.parseInt(console.nextLine());
       System.out.printf("Enter course3 Grade :");
       course3Grade=console.nextLine().charAt(0);
      
       System.out.printf("Enter credit hours course4:");
       course4CreditHours=Integer.parseInt(console.nextLine());
       System.out.printf("Enter course4 Grade :");
       course4Grade=console.nextLine().charAt(0);
      
       //calculate the total grade points
       int totalGradePoints=course1CreditHours*getGradeValue(course1Grade)+
               course2CreditHours*getGradeValue(course2Grade)+
               course3CreditHours*getGradeValue(course3Grade)+
               course4CreditHours*getGradeValue(course4Grade);
      
       //calculate total credit hours
       int totalCreditHours=course1CreditHours+course2CreditHours+
               course3CreditHours+course4CreditHours;
      
       //set gpa value by dividing the total grade points by total credit hours
       gpa=(float)totalGradePoints/totalCreditHours;
   }
  
   public int getGradeValue(char grade)
   {
       if(grade=='A')
           return 4;
       else if(grade=='B')
           return 3;
       else if(grade=='C')
           return 2;
       else if(grade=='D')
           return 1;      
       return 0;
   }
  

   // getter and setter
   public String getId()
   {
       return id;
   }

   public void setId(String id)
   {
       this.id = id;
   }

   public String getName()
   {
       return name;
   }

   public void setName(String name)
   {
       this.name = name;
   }

   public String getMajor()
   {
       return major;
   }

   public void setMajor(String major)
   {
       this.major = major;
   }

   public double getGpa()
   {
       return gpa;
   }
   // print student data
   public void printStudent()
   {
       System.out.println("Student ID: " + id);
       System.out.println("Student name: " + name);
       System.out.println("Student major: " + major);
       System.out.println("Student GPA: " + gpa);
   }

}

-----------------------------------------------------------------------------------------------------------------------------

Sample Output:

Enter credit hours course1:5
Enter course1 Grade :A
Enter credit hours course2:1
Enter course2 Grade :B
Enter credit hours course3:5
Enter course3 Grade :C
Enter credit hours course4:5
Enter course4 Grade :F
Student ID: S12345
Student name: Virat Kohli
Student major: Computer Science
Student GPA: 2.0625