public HashMap<String, Subject> createSubjects() {
		HashMap<String, Subject> subjects = new HashMap<String, Subject>();
		for(String line : courses) {
			Course courseToAdd = new Course(line);
			String courseSubject = courseToAdd.getSubject();
			
			//Collection is empty
			if(subjects.size() == 0){
				//add very first subject
				Subject newSubject = new Subject(courseSubject);
				subjects.put(newSubject.getName(), newSubject);
				newSubject.addCourse(courseToAdd);
				continue;
			}
			
			//if subjects contains this subject already
			if(subjects.containsKey(courseSubject)) {
				//then add to existing subject
				Subject subject = subjects.get(courseSubject);
				//if course already exists
				if(subject.hasCourse(courseToAdd)) {
					Course sameCourse = subject.getCourse(courseToAdd);
					if(sameCourse.hasSameOffering(line)) {
						//add to previous section
						sameCourse.addSectionToCourse(line);
					}
					else {
						//add as a new offering
						sameCourse.addNewOffering(line);
					}
				}
				//if subject doesn't contain this course
				else {
					//then add as a new course
					subject.addCourse(courseToAdd);						
				}
			}
			//If course doesn't belong to any existing subject
			else {
				//then add new subject and add course to that
				Subject newSubject = new Subject(courseSubject);
				subjects.put(newSubject.getName(), newSubject);
				newSubject.addCourse(courseToAdd);
			}
		}
		return subjects;
	}