src/CourseRegistrationStarter/Main.java

@@ -2,13 +2,27 @@ 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
+        Course c1 = new Course("Advanced Programming", "AP1404", 2);
+        Course c2 = new Course("Data Structures", "DS2201", 1);
+        Course c3 = new Course("Database Systems", "DB3301", 3);
+
+        Student student = new Student("Ali", "402222001");
+
+        RegistrationSystem system = new RegistrationSystem();
+
+        system.addCourseToSystem(c1);
+        system.addCourseToSystem(c2);
+        system.addCourseToSystem(c3);
+
+        student.addCourse(c1);
+        student.addCourse(c2);
+
+        student.dropCourse(c1);
+
+        System.out.println("Registered Courses:");
+        student.showRegisteredCourses();
+
+        System.out.println("\nAll Courses in System:");
+        system.showAllCourses();
     }
-}
+}

src/CourseRegistrationStarter/RegistrationSystem.java

@@ -9,16 +9,21 @@ public class RegistrationSystem {
     }
 
     public void addCourseToSystem(Course c) {
-        // TODO: Add the course to the system
+        courses.add(c);
     }
 
     public Course findCourseByCode(String code) {
-        // TODO: Search for a course by course code
-        // Return the matching course if found, otherwise return null
+        for (Course c : courses) {
+            if (c.getCourseCode().equals(code)) {
+                return c;
+            }
+        }
         return null;
     }
 
     public void showAllCourses() {
-        // TODO: Print all courses in the system
+        for (Course c : courses) {
+            System.out.println(c.getCourseName() + " - " + c.getCourseCode() + " - Remaining Capacity: " + c.getCapacity());
+        }
     }
-}
+}

src/CourseRegistrationStarter/Student.java

@@ -21,19 +21,26 @@ public class Student {
     }
 
     public boolean addCourse(Course c) {
-        // TODO: Register the student in the course if capacity allows
-        // Return true if registration was successful, otherwise false
+        if (!registeredCourses.contains(c) && c.getCapacity() > 0) {
+            if (c.reduceCapacity()) {
+                registeredCourses.add(c);
+                return true;
+            }
+        }
         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
+        if (registeredCourses.remove(c)) {
+            c.increaseCapacity();
+            return true;
+        }
         return false;
     }
 
     public void showRegisteredCourses() {
-        // TODO: Print all registered courses
+        for (Course c : registeredCourses) {
+            System.out.println(c.getCourseName() + " - " + c.getCourseCode());
+        }
     }
 }