Question

Write three classes: Student.java, StudentList.java and Course.java with using the concept of linked list.

Answer 1

import java.util.HashMap; import java.util.Objects; public class StudentList { private HashMap<Student, CourseList> studentList; public StudentList() { this.studentList = new HashMap<>(); } public void add(Student student, Course course) { if (this.studentList.containsKey(student)) { CourseList courseListOfStudent = studentList.get(student); courseListOfStudent.add(course); return; } CourseList courseList = new CourseList(); courseList.add(course); studentList.put(student, courseList); } public void display() { for (Student student : studentList.keySet()) { System.out.println("Student Name ::" + student); studentList.get(student).courseList(); System.out.println(); } } public static void main(String[] args) { StudentList studentList = new StudentList(); studentList.add(new Student("srinu"),new Course("MATHS")); studentList.add(new Student("srinu"),new Course("Physics")); studentList.add(new Student("srinu"),new Course("IT")); studentList.add(new Student("ram"),new Course("MATHS")); studentList.add(new Student("ram"),new Course("Chemistry")); studentList.add(new Student("John"),new Course("IT")); studentList.display(); } } class Course { private final String courseName; public Course(String courseName) { this.courseName = courseName; } @Override public String toString() { return courseName; } } class Student { private final String name; public Student(String name) { this.name = name; } @Override public String toString() { return name; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Student student = (Student) o; return Objects.equals(name, student.name); } @Override public int hashCode() { return Objects.hash(name); } } class CourseList { private Node head; public CourseList() { this.head = null; } public void add(Course course) { if (head == null) { head = new Node(course); return; } Node temp = new Node(course); temp.next = head; head = temp; } public void courseList() { System.out.printf("Course List:: "); Node temp = head; while (temp != null) { System.out.printf("%s ", temp.getCourse()); temp = temp.next; } System.out.println(); } } class Node { private Course course; Node next; public Node(Course course) { this.course = course; this.next = null; } public Course getCourse() { return course; } }

Student Name::srinu Course List:: IT Physics MATHS Student Name::Johrn Course List: IT Student Name ::ram Course List:: Chemistry MATHS