The objective of the assignment is to develop your understanding of class relati

ID: 3807807 • Letter: T

Question

The objective of the assignment is to develop your understanding of class relationship in java Topic of assignment: Given the UML, perform the following tasks: Define a class named course Define a class named Transcript which has course as an aggregation class. (you need to create an array of course for the transcript) Define a class named Student which has Transcript as an aggregation class. (you need to create an instance of Transcript for the student) write a test class to test the three classes. The main method should perform the following tasks: Create an instance of Student Add three courses to the transcript of the student Calculate and display the GPA of the student The UML diagram for the classes:

Explanation / Answer

Please find the code with explanations:

public class Course {
   String courseID;
   char grade;
   public Course(String csID, char g) {
       this.courseID = csID;
       this.grade = g;
   }

   public String getCourseID() {
       return courseID;
   }

   public void setCourseID(String csID) {
       this.courseID = csID;
   }

   public char getGrade() {
       return grade;
   }

   public void setGrade(char g) {
       this.grade = g;
   }
}

public class Transcript {
Course[] enrolledCourse;
int numOfCourse;

   public Transcript() {
       enrolledCourse = new Course[1];
       numOfCourse = 0;
   }

   public Transcript(Course[] enrolledCourse) {
       this.enrolledCourse = enrolledCourse;
       this.numOfCourse = enrolledCourse.length;
   }

   // when a course is found, return the corresponding grade
   // when a course is not found, return blank
   //
   public char getCourseGrade(String csID) {
       for(int i=0; i<numOfCourse; i++) {
           if(enrolledCourse[i].getCourseID() == csID) {
               return enrolledCourse[i].getGrade();
           }
       }
       return 'f';
   }

   // no formula given to compute this
   public float getGpa() {
       float total = 0.0f;
       for(int i=0; i<numOfCourse; i++) {
           float score = 0.0f;
           switch(enrolledCourse[i].getGrade()) {
               case 'a':
                   score = 9.0f;
                   break;
               case 'b':
                   score = 8.0f;
                   break;
               case 'c':
                   score = 7.0f;
                   break;
               case 'd':
                   score = 6.0f;
                   break;
               case 'e':
                   score = 5.0f;
                   break;
               case 'f':
                   score = 4.0f;
                   break;
               default:
                   score = 1.0f;
           }
           total += score;
       }
       if(numOfCourse == 0){
           return 0.0f;
       }
       return total/numOfCourse;
   }

   public int getNumOfCourse() {
       numOfCourse = enrolledCourse.length;
       return numOfCourse;
   }

   // Arrays are immutable in Java hence, we need to use a temproary
   // array to store the resultant N+1 courses
   // then assign the temporary array back to the original
   // array
   //
   public boolean addCourse(String csID, char g) {
       Course c = new Course(csID, g);
       Course tempArray[] = new Course[numOfCourse+1];
       for(int i=0; i<numOfCourse; i++) {
           tempArray[i] = enrolledCourse[i];
       }
       tempArray[numOfCourse] = c;
       enrolledCourse = tempArray;
       numOfCourse++;
       return true;
   }

   // find the course.. and then copy the last course to that position
   // Then, set the size of the array to one less than what it is,
   // this operation effectively erases the found course.
   // Finally, return true.
   // If the course was not found, return false.
   //
   public boolean removeCourse(String csID) {
       for(int i=0; i<numOfCourse; i++) {
           if(enrolledCourse[i].getCourseID() == csID) {
               Course temp = enrolledCourse[i];
               enrolledCourse[i] = enrolledCourse[numOfCourse-1];
               numOfCourse--;
               return true;
           }
       }
       return false;
   }

   // find the course. if the course was found, change the grade.
   // if the course was not found, then return false.
   //
   public boolean changeCourseGrade(String csID, char g) {
       for(int i=0; i<numOfCourse; i++) {
           if(enrolledCourse[i].getCourseID() == csID) {
               enrolledCourse[i].setGrade(g);
               return true;
           }
       }
       return false;
   }
}

public class Student {
   String id;
   String name;
   Transcript transcript;

   public Student() {
       transcript = new Transcript();
   }

   public Student(String id, String name, Transcript transcript){
       this.id = id;
       this.name = name;
       this.transcript = transcript;
   }

   public String getID() {
       return id;
   }

   public String getName() {
       return name;
   }

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

   public Transcript getTranscript() {
       return transcript;
   }

   public void setTranscript(Transcript transcript) {
       this.transcript = transcript;
   }
}

public class TestProgram {
   public static void main(String args[]) {
       Student s = new Student();
       Transcript t = s.getTranscript();
       t.addCourse("CS101", 'b');
       t.addCourse("MA101", 'c');
       t.addCourse("NW101", 'a');
       s.setTranscript(t);

System.out.println(s.getTranscript().getGpa());
}
}