feat: implement required features

src/CourseRegistrationStarter/Course.java

@@ -1,37 +1,45 @@
 package CourseRegistrationStarter;
 
-public class Course {
+public class Course
+{
     private String courseName;
     private String courseCode;
     private int capacity;
 
-    public Course(String courseName, String courseCode, int capacity) {
+    public Course(String courseName, String courseCode, int capacity)
+    {
         this.courseName = courseName;
         this.courseCode = courseCode;
         this.capacity = capacity;
     }
 
-    public String getCourseName() {
+    public String getCourseName()
+    {
         return courseName;
     }
 
-    public String getCourseCode() {
+    public String getCourseCode()
+    {
         return courseCode;
     }
 
-    public int getCapacity() {
+    public int getCapacity()
+    {
         return capacity;
     }
 
-    public boolean reduceCapacity() {
-        if (capacity > 0) {
+    public boolean reduceCapacity()
+    {
+        if (capacity > 0)
+        {
             capacity--;
             return true;
         }
         return false;
     }
 
-    public void increaseCapacity() {
+    public void increaseCapacity()
+    {
         capacity++;
     }
 }

src/CourseRegistrationStarter/Main.java

@@ -1,14 +1,70 @@
 package CourseRegistrationStarter;
 
-public class Main {
-    public static void main(String[] args) {
-        // TODO:
-        // 1. Create at least 3 courses
-        // 2. Create 1 student
-        // 3. Create a registration system
-        // 4. Add courses to the system
-        // 5. Register the student in some courses
-        // 6. Drop one course
-        // 7. Print the final registered course list
+public class Main 
+{
+    public static void main(String[] args) 
+    {
+        // 1. Creating courses
+        Course ap = new Course("Advanced Programming", "AP1404", 2);
+        Course ds = new Course("Data Structures", "DS2201", 1);
+        Course db = new Course("Database Systems", "DB3301", 3);
+        Course algo = new Course("Algorithms", "CS401", 2); // Another course for testing limits
+
+        // 2. Creating student
+        Student student = new Student("steve", "1010101010101");
+
+        // 3. Creating a registration system
+        RegistrationSystem registrationSystem = new RegistrationSystem();
+
+        // 4. Adding courses to the system
+        registrationSystem.addCourseToSystem(ap);
+        registrationSystem.addCourseToSystem(ds);
+        registrationSystem.addCourseToSystem(db);
+        registrationSystem.addCourseToSystem(algo);
+        
+        // Attempting to add a duplicate course code (should be prevented)
+        registrationSystem.addCourseToSystem(new Course("Advanced Programming 2", "AP1404", 5));
+
+
+        // 5. Registering the student in some courses
+        System.out.println("\n------- Attempting Course Registrations -------");
+        student.addCourse(ap);      // Success
+        student.addCourse(ds);      // Success
+        student.addCourse(db);      // Success
+
+        // Attempting to register for a 4th course (should fail due to the course limit)
+        student.addCourse(algo);    // Failure!
+
+        // Attempting to register for an already registered course (should fail)
+        student.addCourse(ap);      // Failure!
+
+        // 6. Dropping one course
+        System.out.println("\n------- Attempting to Drop a Course -------");
+        // Attempting to drop a course the student is not registered in
+        student.dropCourse(algo);   // Failure!
+        // Successfully drop a course
+        student.dropCourse(ds);     // Success
+
+        // 7. Printing final results
+        student.showRegisteredCourses();
+        registrationSystem.showAllCourses();
+
+        // finding courses
+        System.out.println("\n------- Searching for Courses -------");
+        String searchCode = "DB3301";
+        Course foundByCode = registrationSystem.findCourseByCode(searchCode);
+
+        if (foundByCode != null)
+            System.out.println("Found course by code '" + searchCode + "': " + foundByCode.getCourseName());
+        else
+            System.out.println("Course with code '" + searchCode + "' is not found.");
+
+        String searchName = "data structures";
+        Course foundByName = registrationSystem.findCourseByName(searchName);
+
+        if (foundByName != null)
+            System.out.println("Found course by name '" + searchName + "': " + foundByName.getCourseName() + " (" + foundByName.getCourseCode() + ")");
+        else
+            System.out.println("Course with name '" + searchName + "' not found.");
     }
 }

src/CourseRegistrationStarter/RegistrationSystem.java

@@ -1,24 +1,62 @@
 package CourseRegistrationStarter;
 import java.util.ArrayList;
+import java.util.Objects;
 
-public class RegistrationSystem {
+public class RegistrationSystem
+{
     private ArrayList<Course> courses;
 
-    public RegistrationSystem() {
+    public RegistrationSystem()
+    {
         courses = new ArrayList<>();
     }
 
-    public void addCourseToSystem(Course c) {
-        // TODO: Add the course to the system
+    public void addCourseToSystem(Course c)
+    {
+        if (findCourseByCode(c.getCourseCode()) == null)
+        {
+            courses.add(c);
+            System.out.println("Course added to system: " + c.getCourseName() + " (" + c.getCourseCode() + ")");
+        }
+        else
+            System.out.println("Error: Course with code " + c.getCourseCode() + " already exists in the system.");
     }
 
-    public Course findCourseByCode(String code) {
-        // TODO: Search for a course by course code
-        // Return the matching course if found, otherwise return null
+    public Course findCourseByCode(String code)
+    {
+        for (Course c : courses)
+        {
+            if (c.getCourseCode().equals(code))
+                return c;
+        }
+
         return null;
     }
 
-    public void showAllCourses() {
-        // TODO: Print all courses in the system
+    public Course findCourseByName(String name)
+    {
+        for (Course c : courses)
+        {
+            // Case-insensitive search
+            if (c.getCourseName().equalsIgnoreCase(name))
+                return c;
+        }
+        return null;
+    }
+
+    public void showAllCourses()
+    {
+        System.out.println("\n------- All Courses in System -------");
+
+        if (courses.isEmpty())
+        {
+            System.out.println("No course is available in the system.");
+            return;
+        }
+        for (Course c : courses)
+        {
+            System.out.println("- " + c.getCourseName() + " (" + c.getCourseCode() + ")");
+            System.out.println("  Remaining Capacity: " + Objects.toString(c.getCapacity(), "N/A"));
+        }
     }
 }

src/CourseRegistrationStarter/Student.java

@@ -1,39 +1,83 @@
 package CourseRegistrationStarter;
 import java.util.ArrayList;
 
-public class Student {
+public class Student
+{
     private String name;
     private String studentId;
     private ArrayList<Course> registeredCourses;
 
-    public Student(String name, String studentId) {
+    private static final int MAX_COURSES = 3;
+
+    public Student(String name, String studentId)
+    {
         this.name = name;
         this.studentId = studentId;
         this.registeredCourses = new ArrayList<>();
     }
 
-    public String getName() {
+    public String getName()
+    {
         return name;
     }
 
-    public String getStudentId() {
+    public String getStudentId()
+    {
         return studentId;
     }
 
-    public boolean addCourse(Course c) {
-        // TODO: Register the student in the course if capacity allows
-        // Return true if registration was successful, otherwise false
+    public boolean addCourse(Course c)
+    {
+        if (registeredCourses.contains(c))
+        {
+            System.out.println("Error: Already registered in " + c.getCourseName() + " (" + c.getCourseCode() + ").");
+            return false;
+        }
+
+        if (registeredCourses.size() >= MAX_COURSES)
+        {
+            System.out.println("Error: Cannot register for " + c.getCourseName() + ". Maximum of " + MAX_COURSES + " courses reached.");
+            return false;
+        }
+
+        // Check and reduce capacity
+        if (c.reduceCapacity())
+        {
+            registeredCourses.add(c);
+            System.out.println("Successfully registered in " + c.getCourseName() + " (" + c.getCourseCode() + ").");
+            return true;
+        }
+
+        System.out.println("Error: Failed to register in " + c.getCourseName() + " (" + c.getCourseCode() + ") due to reaching maximum capacity.");
         return false;
     }
 
-    public boolean dropCourse(Course c) {
-        // TODO: Remove the course from the student's list
-        // Restore the course capacity if removal was successful
-        // Return true if the course was dropped, otherwise false
+    public boolean dropCourse(Course c)
+    {
+        if (registeredCourses.remove(c))
+        {
+            c.increaseCapacity();
+            System.out.println("Successfully dropped " + c.getCourseName() + " (" + c.getCourseCode() + ").");
+            return true;
+        }
+
+        System.out.println("Error: Course '" + c.getCourseName() + "' (" + c.getCourseCode() + ") was not found in registered courses.");
         return false;
     }
 
-    public void showRegisteredCourses() {
-        // TODO: Print all registered courses
+    public void showRegisteredCourses()
+    {
+        System.out.println("\n------- " + name + "'s Registered Courses -------");
+
+        if (registeredCourses.isEmpty())
+        {
+            System.out.println("No course is registered.");
+            return;
+        }
+
+        for (Course c : registeredCourses)
+            System.out.println("- " + c.getCourseName() + " (" + c.getCourseCode() + ")");
+
+        System.out.println("Total courses: " + registeredCourses.size() + "/" + MAX_COURSES);
     }
 }