Question

How to complete these methods:

/**
   * Returns a reference to the course with title equals to the argument. This
   * method searches in the courses stored in the HashMap {@code courses} to find
   * the course whose title equals to the argument {@code title}. If the course is
   * not found, {@code null} is returned.
   *
   * @param title the title of the course
   * @return a reference to the course, or {@code null} if the course is not
   * found.
   */
   public static Course getCourseByTitle(String title) {

   }

   /**
   * Returns a reference to the Student whose name equals to the argument. This
   * method searches in the students stored in the HashMap {@code students} to
   * find the student whose name equals to the argument {@code name}. If the
   * student is not found, {@code null} is returned.
   *
   * @param name the student name
   * @return the student whose name is specified in the argument, or {@code null}
   * if the student is not found
   */
   public static Student getStudentByName(String name) {

   }

   /**
   * Add a new student entry to {@code students} HashMap.
   *
   * @param id id of the new student
   * @param student object of the new student
   * @throws Exception if the new {@code id} exists in the {@code students}
   * HashMap
   */
   public static void addStudent(String id, Student student) throws Exception {

   }

   /**
   * Remove an existing student entry from {@code students} HashMap.
   *
   * @param id the 'id' of the student to be removed
   * @throws Exception if the {@code id} does not exist in the {@code students}
   * HashMap
   */
   public static void removeStudent(String id) throws Exception {

   }

   /**
   * Returns the entry in the {@link offerings} list that has the information
   * provided in the arguments. If the entry is not found, {@code null} is
   * returned.
   *
   * @param courseCode the code of the course offered
   * @param section section of the course
   * @param term term
   * @param year year
   * @return Returns the entry in the {@link offerings} list that has the
   * information provided in the arguments
   */
   public static CourseOffering getCourseOffering(String courseCode, char section, char term, int year) {

   }

   public static void main(String[] args) {
       // Reading the list of course from the file COURSES_FILE
       readCourses();
       if (courses.isEmpty())
           System.err.println("courses shall not be empty");

       // Reading the list of course from the file STUDENTS_FILE
       readStudents();
       if (students.isEmpty())
           System.err.println("students shall not be empty");
       // add few offerings
       addOfferings();
       if (offerings.isEmpty())
           System.err.println("offerings shall not be empty");

       CourseOffering courseOffer1 = getCourseOffering("EECS2030", 'A', 'W', 2020);
       if (courseOffer1 != null) {
           // enroll the student whose name is "Maximilian" in the first offering
           Student s = getStudentByName("Maximilian");
           if (s != null) {
               try {
                   enroll(s, courseOffer1);
                   System.out.println(s + " is enrolled in " + courseOffer1);
               } catch (Exception e) {
                   System.err.println("Was unable to enroll " + s + " in " + courseOffer1 + "\n" + e.getMessage());
               }
           } else {
               System.err.println("Student Maximilian is not found");
           }

           s = getStudentByName("Alphonso");
           if (s != null) {
               try {
                   enroll(s, courseOffer1);
                   System.out.println(s + " is enrolled in " + courseOffer1);
               } catch (Exception e) {
                   System.err.println("Was unable to enroll " + s + " in " + courseOffer1 + "\n" + e.getMessage());
               }
           } else {
               System.err.println("Student Maximilian is not found");
           }

       } else {
           System.err.println("Course EECS2030 is not offered in W2020");
       }
   }

   /**
   * Populate the course offerings list with few entries.
   */
   public static void addOfferings() {
       offerings.add(new CourseOffering(courses.get("EECS1021"), 20, 'F', 'A', 2020, LocalDate.of(2020, 9, 30)));
       offerings.add(new CourseOffering(getCourseByTitle("Object Oriented Programming"), 20, 'F', 'B', 2020,
               LocalDate.of(2020, 9, 30)));
       offerings.add(new CourseOffering(courses.get("EECS1022"), 30, 'F', 'A', 2020, LocalDate.of(2020, 9, 30)));
       offerings.add(new CourseOffering(courses.get("EECS2030"), 15, 'W', 'A', 2020, LocalDate.of(2020, 9, 30)));
   }

   /**
   * Read a list of courses from the file {@link COURSES_FILE} and populate
   * {@code course} HashMap.
   */
   public static void readCourses() {
       Scanner inputStream = null;
       try {
           inputStream = new Scanner(new FileInputStream(PATH + "/eecs2030/lab4/" + COURSES_FILE));
       } catch (FileNotFoundException e) {
           System.out.println("File Courses.csv was not found");
           System.out.println("or could not be opened.");
           System.out.println(e.toString());
           System.exit(0);
       }
       String line;
       while (inputStream.hasNext()) {
           line = inputStream.nextLine();
           String[] info = line.split(",");
           Course c = new Course(info[0].trim(), info[1].trim());
           if (info.length > 2) {
               String[] preList = info[2].split(";");
               for (String p : preList)
                   c.addPrerequisite(p.trim());
           }
           courses.put(c.getCode(), c);
       }
       inputStream.close();
   }

   /**
   * Read a list of students from the file {@link STUDENTS_FILE} and populate
   * {@code students} HashMap.
   */
   public static void readStudents() {
       Scanner inputStream = null;
       try {
           inputStream = new Scanner(new FileInputStream(PATH + "/eecs2030/lab4/" + STUDENTS_FILE));
       } catch (FileNotFoundException e) {
           System.out.println("File " + STUDENTS_FILE + " was not found");
           System.out.println("or could not be opened.");
           System.out.println(e.toString());
           System.exit(0);
       }
       String line;
       while (inputStream.hasNext()) {
           line = inputStream.nextLine();
           String[] s = line.split(",");
           String id = s[0].trim();
           String name = s[1].trim();
           int y = Integer.parseInt(s[2].trim());
           int m = Integer.parseInt(s[3].trim());
           int d = Integer.parseInt(s[4].trim());
           String email = s[5].trim();
           LocalDate joinDate = LocalDate.of(y, m, d);
           Student stu = new Student(id, name, joinDate, email);
           if (s.length > 6) {
               String[] cc = s[6].split(";");
               for (String w : cc) {
                   stu.completeCourse(w.trim());
               }
           }
           students.put(stu.getId(), stu);
       }
       inputStream.close();

Answer 1

as your code doesnot have any class i am assuming this is only for understanding purpose, this code will not run.

/**
   * Returns a reference to the course with title equals to the argument. This
   * method searches in the courses stored in the HashMap {@code courses} to find
   * the course whose title equals to the argument {@code title}. If the course is
   * not found, {@code null} is returned.
   *
   * @param title the title of the course
   * @return a reference to the course, or {@code null} if the course is not
   * found.
   */
   public static Course getCourseByTitle(String title) {
       if(!Courses.containsValue(title))
       return null;
       for (Map.Entry<String,String> entry : Courses.entrySet())
       {
           if(entry.getValue().contains(title))
           return entry;
       }
   }

   /**
   * Returns a reference to the Student whose name equals to the argument. This
   * method searches in the students stored in the HashMap {@code students} to
   * find the student whose name equals to the argument {@code name}. If the
   * student is not found, {@code null} is returned.
   *
   * @param name the student name
   * @return the student whose name is specified in the argument, or {@code null}
   * if the student is not found
   */
   public static Student getStudentByName(String name) {
       if(!students.containsValue(name))
       return null;
       for (Map.Entry<String,String> entry : students.entrySet())
       {
           if(entry.getValue().contains(name))
           return entry;
       }
   }

   /**
   * Add a new student entry to {@code students} HashMap.
   *
   * @param id id of the new student
   * @param student object of the new student
   * @throws Exception if the new {@code id} exists in the {@code students}
   * HashMap
   */
   public static void addStudent(String id, Student student) throws Exception {
       student temp = new student(id, student);
       students.put(c.getCode(), c);
   }

   /**
   * Remove an existing student entry from {@code students} HashMap.
   *
   * @param id the 'id' of the student to be removed
   * @throws Exception if the {@code id} does not exist in the {@code students}
   * HashMap
   */
   public static void removeStudent(String id) throws Exception {
       for (Map.Entry<String,String> entry : students.entrySet())
       {
           if(entry.getValue().contains(name))
           students.remove(entry.getKey());
       }
   }

   /**
   * Returns the entry in the {@link offerings} list that has the information
   * provided in the arguments. If the entry is not found, {@code null} is
   * returned.
   *
   * @param courseCode the code of the course offered
   * @param section section of the course
   * @param term term
   * @param year year
   * @return Returns the entry in the {@link offerings} list that has the
   * information provided in the arguments
   */
   public static CourseOffering getCourseOffering(String courseCode, && char section, char term, int year) {
       for (String temp : offerings)
       {
           if(temp.contains(courseCode) && temp.contains(courseCode) && section.contains(term) && temp.contains(year))
           {
               return temp;
           }
       }
       return null;
   }

   public static void main(String[] args) {
       // Reading the list of course from the file COURSES_FILE
       readCourses();
       if (courses.isEmpty())
           System.err.println("courses shall not be empty");

       // Reading the list of course from the file STUDENTS_FILE
       readStudents();
       if (students.isEmpty())
           System.err.println("students shall not be empty");
       // add few offerings
       addOfferings();
       if (offerings.isEmpty())
           System.err.println("offerings shall not be empty");

       CourseOffering courseOffer1 = getCourseOffering("EECS2030", 'A', 'W', 2020);
       if (courseOffer1 != null) {
           // enroll the student whose name is "Maximilian" in the first offering
           Student s = getStudentByName("Maximilian");
           if (s != null) {
               try {
                   enroll(s, courseOffer1);
                   System.out.println(s + " is enrolled in " + courseOffer1);
               } catch (Exception e) {
                   System.err.println("Was unable to enroll " + s + " in " + courseOffer1 + "\n" + e.getMessage());
               }
           } else {
               System.err.println("Student Maximilian is not found");
           }

           s = getStudentByName("Alphonso");
           if (s != null) {
               try {
                   enroll(s, courseOffer1);
                   System.out.println(s + " is enrolled in " + courseOffer1);
               } catch (Exception e) {
                   System.err.println("Was unable to enroll " + s + " in " + courseOffer1 + "\n" + e.getMessage());
               }
           } else {
               System.err.println("Student Maximilian is not found");
           }

       } else {
           System.err.println("Course EECS2030 is not offered in W2020");
       }
   }

   /**
   * Populate the course offerings list with few entries.
   */
   public static void addOfferings() {
       offerings.add(new CourseOffering(courses.get("EECS1021"), 20, 'F', 'A', 2020, LocalDate.of(2020, 9, 30)));
       offerings.add(new CourseOffering(getCourseByTitle("Object Oriented Programming"), 20, 'F', 'B', 2020,
               LocalDate.of(2020, 9, 30)));
       offerings.add(new CourseOffering(courses.get("EECS1022"), 30, 'F', 'A', 2020, LocalDate.of(2020, 9, 30)));
       offerings.add(new CourseOffering(courses.get("EECS2030"), 15, 'W', 'A', 2020, LocalDate.of(2020, 9, 30)));
   }

   /**
   * Read a list of courses from the file {@link COURSES_FILE} and populate
   * {@code course} HashMap.
   */
   public static void readCourses() {
       Scanner inputStream = null;
       try {
           inputStream = new Scanner(new FileInputStream(PATH + "/eecs2030/lab4/" + COURSES_FILE));
       } catch (FileNotFoundException e) {
           System.out.println("File Courses.csv was not found");
           System.out.println("or could not be opened.");
           System.out.println(e.toString());
           System.exit(0);
       }
       String line;
       while (inputStream.hasNext()) {
           line = inputStream.nextLine();
           String[] info = line.split(",");
           Course c = new Course(info[0].trim(), info[1].trim());
           if (info.length > 2) {
               String[] preList = info[2].split(";");
               for (String p : preList)
                   c.addPrerequisite(p.trim());
           }
           courses.put(c.getCode(), c);
       }
       inputStream.close();
   }

   /**
   * Read a list of students from the file {@link STUDENTS_FILE} and populate
   * {@code students} HashMap.
   */
   public static void readStudents() {
       Scanner inputStream = null;
       try {
           inputStream = new Scanner(new FileInputStream(PATH + "/eecs2030/lab4/" + STUDENTS_FILE));
       } catch (FileNotFoundException e) {
           System.out.println("File " + STUDENTS_FILE + " was not found");
           System.out.println("or could not be opened.");
           System.out.println(e.toString());
           System.exit(0);
       }
       String line;
       while (inputStream.hasNext()) {
           line = inputStream.nextLine();
           String[] s = line.split(",");
           String id = s[0].trim();
           String name = s[1].trim();
           int y = Integer.parseInt(s[2].trim());
           int m = Integer.parseInt(s[3].trim());
           int d = Integer.parseInt(s[4].trim());
           String email = s[5].trim();
           LocalDate joinDate = LocalDate.of(y, m, d);
           Student stu = new Student(id, name, joinDate, email);
           if (s.length > 6) {
               String[] cc = s[6].split(";");
               for (String w : cc) {
                   stu.completeCourse(w.trim());
               }
           }
           students.put(stu.getId(), stu);
       }
       inputStream.close();

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