Objectives: CS 3340 Object Oriented Programming To practice more with collection
ID: 3863287 • Letter: O
Question
Objectives:
CS 3340 Object Oriented Programming
To practice more with collections and exceptions.
Assignment:
Your job is to extend the Registration System we built in class in 3 ways:
Support a new type of class called a OpenUniversity student. These students do not have an ID, but they do have a phone number. Two students are the same if they have the same name and phone number.
Allow each course to have a set of Open University students, in addition to regular students. There should be 2 capacities for each course, the number of regular students and the number of Open University students.
The number of Open Unversity students should not exceed the number of regular students at any time or else an exception should be thrown.
It should be possible to delete students from a course using a new "ds" command. When that command is entered, the system should ask the user for the ID of the student and then search both the full time students and Open University student lists for that student in the course. If found, that student should be removed from that list.
Student Java:
package mar06registration;
import java.util.Objects;
public class Student {
private String name;
private String id;
public Student(String name, String id) {
this.name = name;
this.id = id;
}
@Override
public int hashCode() {
int hash = 7;
hash = 37 * hash + Objects.hashCode(this.id);
return hash;
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
final Student other = (Student) obj;
if (!Objects.equals(this.id, other.id)) {
return false;
}
return true;
}
private String getId() {
return this.id;
}
}
Course.Java
package mar06registration;
import java.util.HashSet;
import java.util.Set;
public class Course {
private String name;
private int capacity;
private Set<Student> students;
public Course(String name, int capacity) {
this(name);
this.capacity = capacity;
}
public Course(String courseName) {
students = new HashSet<Student>();
this.name = courseName;
}
public String getName() {
return name;
}
void addStudent(Student student) {
if (students.contains(student)) {
throw new RuntimeException("Student already in course!");
}
else if (students.size() == this.capacity) {
throw new RuntimeException("Course already full");
}
students.add(student);
}
}
RegistrationSystem.java
package mar06registration;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;
public class RegistrationSystem {
private Map<String, Course> school;
public RegistrationSystem() {
school = new HashMap<String, Course>();
}
private static void out(String s) {
System.out.print(s);
}
private static void outln(String s) {
System.out.println(s);
}
public static void main(String[] args) {
RegistrationSystem rs = new RegistrationSystem();
Scanner s = new Scanner(System.in);
boolean done = false;
do {
out("What next? ");
try {
String cmd = s.next();
s.nextLine();
switch (cmd) {
case "q": {
done = true;
outln("Goodbye!");
break;
}
case "ac": {
handleAddCourse(s, rs);
break;
}
case "as": {
handleAddStudent(s, rs);
break;
}
default:
outln("I do not understand you!");
break;
}
} catch (Exception e) {
outln("ERROR: "+e.getMessage());
}
} while (!done);
}
private static void handleAddStudent(Scanner s, RegistrationSystem rs) {
out("Student name: ");
String name = s.next();
s.nextLine();
out("Student ID: ");
String id = s.next();
s.nextLine();
out("Course: ");
String courseName = s.next();
s.nextLine();
Student student = new Student(name, id);
Course course = new Course(courseName);
rs.addStudentToCourse(student, course);
outln("Student added!");
}
private static void handleAddCourse(Scanner s, RegistrationSystem rs) {
out("Course name: ");
String name = s.next();
s.nextLine();
out("Course capacity: ");
int capacity = s.nextInt();
s.nextLine();
Course c = new Course(name, capacity);
rs.addCourse(c);
outln("Course added");
}
private void addCourse(Course c) {
if (courseExist(c)) {
throw new RuntimeException("Course already exists");
}
addCourseToSchool(c);
}
private boolean courseExist(Course c) {
return school.get(c.getName()) != null;
}
private void addCourseToSchool(Course c) {
school.put(c.getName(), c);
}
private void addStudentToCourse(Student student, Course course) {
Course c = school.get(course.getName());
if (c == null) {
throw new RuntimeException("No such course!");
}
c.addStudent(student);
}
}
Explanation / Answer
1. Student.java:
import java.util.Objects;
public class Student {
private String name;
private String id;
public Student(String name, String id) {
this.name = name;
this.id = id;
}
@Override
public int hashCode() {
int hash = 7;
hash = 37 * hash + Objects.hashCode(this.id);
return hash;
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
final Student other = (Student) obj;
if (!Objects.equals(this.id, other.id)) {
return false;
}
return true;
}
public String getId() {
return this.id;
}
}
2. Course.java:
import java.util.HashSet;
import java.util.Set;
public class Course {
private String name;
private int capacity;
private int openCapacity;
private Set<Student> students;
private Set<OpenUniversity> openUniversity;
public Course(String name, int capacity, int openCapacity) {
this(name);
if(capacity < openCapacity){
throw new RuntimeException("Open Capacity cannot be greater than Capacity!");
}
this.capacity = capacity;
this.openCapacity = openCapacity;
}
public Course(String courseName) {
students = new HashSet<Student>();
openUniversity = new HashSet<OpenUniversity>();
this.name = courseName;
}
public String getName() {
return name;
}
void addStudent(Student student) {
if (students.contains(student)) {
throw new RuntimeException("Student already in course!");
} else if (students.size() == this.capacity) {
throw new RuntimeException("Course already full");
}
students.add(student);
}
void addOpenUniversityStudent(OpenUniversity student) {
if (openUniversity.contains(student)) {
throw new RuntimeException("Student already in course!");
} else if (openUniversity.size() == this.openCapacity) {
System.out.println(openUniversity.size());
throw new RuntimeException("Course already full");
}
openUniversity.add(student);
}
public Set<Student> getStudents() {
return students;
}
public void setStudents(Set<Student> students) {
this.students = students;
}
}
3. RegistrationSystem.java:
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
public class RegistrationSystem {
private Map<String, Course> school;
public RegistrationSystem() {
school = new HashMap<String, Course>();
}
private static void out(String s) {
System.out.print(s);
}
private static void outln(String s) {
System.out.println(s);
}
public static void main(String[] args) {
RegistrationSystem rs = new RegistrationSystem();
Scanner s = new Scanner(System.in);
boolean done = false;
do {
out("What next? ");
try {
String cmd = s.next();
s.nextLine();
switch (cmd) {
case "q": {
done = true;
outln("Goodbye!");
break;
}
case "ac": {
handleAddCourse(s, rs);
break;
}
case "as": {
handleAddStudent(s, rs);
break;
}
case "ou": {
handleOpenUniversity(s, rs);
break;
}
case "ds": {
handleDeleteStudent(s, rs);
break;
}
default:
outln("I do not understand you!");
break;
}
} catch (Exception e) {
outln("ERROR: " + e.getMessage());
}
} while (!done);
}
private static void handleDeleteStudent(Scanner s, RegistrationSystem rs) {
out("Student ID: ");
String id = s.next();
rs.deleteStudent(id);
}
private void deleteStudent(String id) {
List<Course> allCourse = new ArrayList<>();
Collection c = school.values();
allCourse.addAll(c);
Set<Student> studentSet = null;
List<Student> studentList = null;
Student student;
for(int i = 0; i < allCourse.size(); i++){
studentSet = allCourse.get(i).getStudents();
studentList = new ArrayList<>(studentSet);
for(int j = 0; j < allCourse.size(); j++){
student = studentList.get(j);
String studentId = student.getId();
if(studentId == id){
studentList.remove(j);
}
}
studentSet = new HashSet<>(studentList);
allCourse.get(i).setStudents(studentSet);
}
System.out.println("Students Deleted");
}
private static void handleOpenUniversity(Scanner s, RegistrationSystem rs) {
out("Open University Student name: ");
String name = s.next();
s.nextLine();
out("Student Phone: ");
String phone = s.next();
s.nextLine();
out("Course: ");
String courseName = s.next();
s.nextLine();
OpenUniversity student = new OpenUniversity(name, phone);
Course course = new Course(courseName);
rs.addOpenUniversityStudentToCourse(student, course);
outln("Open University Student added!");
}
private static void handleAddStudent(Scanner s, RegistrationSystem rs) {
out("Student name: ");
String name = s.next();
s.nextLine();
out("Student ID: ");
String id = s.next();
s.nextLine();
out("Course: ");
String courseName = s.next();
s.nextLine();
Student student = new Student(name, id);
Course course = new Course(courseName);
rs.addStudentToCourse(student, course);
outln("Student added!");
}
private static void handleAddCourse(Scanner s, RegistrationSystem rs) {
out("Course name: ");
String name = s.next();
s.nextLine();
out("Course capacity: ");
int capacity = s.nextInt();
out("Course Open University capacity: ");
int openCapacity = s.nextInt();
s.nextLine();
Course c = new Course(name, capacity, openCapacity);
rs.addCourse(c);
outln("Course added");
}
private void addCourse(Course c) {
if (courseExist(c)) {
throw new RuntimeException("Course already exists");
}
addCourseToSchool(c);
}
private boolean courseExist(Course c) {
return school.get(c.getName()) != null;
}
private void addCourseToSchool(Course c) {
school.put(c.getName(), c);
}
private void addStudentToCourse(Student student, Course course) {
Course c = school.get(course.getName());
if (c == null) {
throw new RuntimeException("No such course!");
}
c.addStudent(student);
}
private void addOpenUniversityStudentToCourse(OpenUniversity student, Course course) {
Course c = school.get(course.getName());
if (c == null) {
throw new RuntimeException("No such course!");
}
c.addOpenUniversityStudent(student);
}
}
4. OpenUniversity.java:
import java.util.Objects;
public class OpenUniversity {
private String name;
private String phoneNumber;
public OpenUniversity(String name, String phoneNumber) {
super();
this.name = name;
this.phoneNumber = phoneNumber;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPhoneNumber() {
return phoneNumber;
}
public void setPhoneNumber(String phoneNumber) {
this.phoneNumber = phoneNumber;
}
@Override
public int hashCode() {
int hash = 7;
hash = 37 * hash + Objects.hashCode(this.phoneNumber);
return hash;
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
final OpenUniversity other = (OpenUniversity) obj;
if (!Objects.equals(this.phoneNumber, other.phoneNumber)) {
return false;
}
if (!Objects.equals(this.name, other.name)) {
return false;
}
return true;
}
}
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