Exercises: Objects and Classes Part 2

Work on these exercises in the IntelliJ java-web-dev-projects/classes-part-two/exercises project. You will update your Student.java file by implementing the addGrade and getGradeLevel methods that were sketched out in the Instance Methods section.

1. The getGradeLevel Method

This method returns the student’s level based on the number of credits they have earned: Freshman (0-29 credits), Sophomore (30-59 credits), Junior (60-89 credits), or Senior (90+ credits).

public static String getGradeLevel(int credits) {
   if (credits <= 29){
      return "freshman";
   } else if (credits <= 59){
      return "sophomore";
   } else if (credits <= 89) {
      return "junior";
   } else {
      return "senior";
   }
}

2. The addGrade Method

This method accepts two parameters—a number of course credits and a numerical grade (0.0-4.0). With this data, you need to update the student’s GPA.

GPA Information

GPA is computed via the formula:

gpa = (total quality score) / (total number of credits)

  1. The quality score for a class is found by multiplying the letter grade score (0.0-4.0) by the number of credits.

  2. The total quality score is the sum of the quality scores for all classes.

For example, if a student received an “A” (worth 4 points) in a 3-credit course and a “B” (worth 3 points) in a 4-credit course, their total quality score would be: 4.0 * 3 + 3.0 * 4 = 24. Their GPA would then be 24 / 7 = 3.43.

Determine the New GPA

To update the student’s GPA:

  1. Calculate their current total quality score by using the formula gpa * numberOfCredits.
  2. Use the new course grade and course credits to update their total quality score.
  3. Update the student’s total numberOfCredits.
  4. Compute their new GPA.
1
2
3
4
5
6

public void addGrade(int courseCredits, double grade) {
   double totalQualityScore = this.gpa * this.numberOfCredits;
   totalQualityScore += courseCredits * grade;
   this.numberOfCredits += courseCredits;
   this.gpa = totalQualityScore/this.numberOfCredits;
}

3. toString and equals

Add custom equals() and toString() methods to the Student class.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22

public String toString() {
   
   String studentReport = String.format("%s is a %s with %d credits and a GPA of %.2f", this.name, this.getGradeLevel(this.numberOfCredits), this.getNumberOfCredits(), this.getGpa());
   return studentReport;
}

public boolean equals(Object toBeCompared) {
   if (toBeCompared == this) {
      return true;
   }

   if (toBeCompared == null) {
      return false;
   }

   if (toBeCompared.getClass() != getClass()) {
      return false;
   }

   Student theStudent = (Student) toBeCompared;
   return theStudent.getStudentId() == getStudentId();
}

Add custom equals() and toString() methods to the Course class which you started in the exercises for the previous chapter .