.idea/.name

@@ -0,0 +1 @@
+Course.java

src/CourseRegistrationStarter/Main.java

@@ -2,13 +2,34 @@ 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
+        // 1. Create courses
+        Course c1 = new Course("Advanced Programming", "AP1404", 2);
+        Course c2 = new Course("Data Structures", "DS2201", 1);
+        Course c3 = new Course("Database Systems", "DB3301", 3);
+
+        // 2. Create student
+        Student student = new Student("Ali", "402222001");
+
+        // 3. Create registration system
+        RegistrationSystem system = new RegistrationSystem();
+
+        // 4. Add courses to system
+        system.addCourseToSystem(c1);
+        system.addCourseToSystem(c2);
+        system.addCourseToSystem(c3);
+
+        // 5. Register student in courses
+        student.addCourse(system.findCourseByCode("AP1404"));
+        student.addCourse(system.findCourseByCode("DS2201"));
+
         // 6. Drop one course
-        // 7. Print the final registered course list
+        student.dropCourse(system.findCourseByCode("DS2201"));
+
+        // 7. Print final results
+        System.out.println("===== FINAL STUDENT COURSES =====");
+        student.showRegisteredCourses();
+
+        System.out.println("\n===== SYSTEM COURSES =====");
+        system.showAllCourses();
     }
 }

src/CourseRegistrationStarter/RegistrationSystem.java

@@ -9,16 +9,26 @@ public class RegistrationSystem {
     }
 
     public void addCourseToSystem(Course c) {
-        // TODO: Add the course to the system
+        courses.add(c);
     }
-
+// we loop through all courses and check it with its code
     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;
     }
-
+// List all courses
     public void showAllCourses() {
-        // TODO: Print all courses in the system
+        System.out.println("All Courses in System:");
+        for (Course c : courses) {
+            System.out.println(
+                    c.getCourseName() + " | " +
+                            c.getCourseCode() + " | Capacity: " +
+                            c.getCapacity()
+            );
+        }
     }
 }

src/CourseRegistrationStarter/Student.java

@@ -2,9 +2,9 @@ package CourseRegistrationStarter;
 import java.util.ArrayList;
 
 public class Student {
-    private String name;
-    private String studentId;
-    private ArrayList<Course> registeredCourses;
+    private final String name;
+    private final String studentId;
+    private final ArrayList<Course> registeredCourses;
 
     public Student(String name, String studentId) {
         this.name = name;
@@ -21,19 +21,32 @@ 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
+        // Prevent duplicate registration
+        if (registeredCourses.contains(c)) {
+            return false;
+        }
+
+        // Try to reduce capacity first
+        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
+    public boolean dropCourse(Course c) {if (registeredCourses.remove(c)) {
+        // after removing course, its capacity will be increased
+        c.increaseCapacity();
+        return true;
+    }
         return false;
     }
-
+// List all registered courses of student
     public void showRegisteredCourses() {
-        // TODO: Print all registered courses
+        System.out.println("Registered courses for " + name + ":");
+        for (Course c : registeredCourses) {
+            System.out.println(c.getCourseName() + " (" + c.getCourseCode() + ")");
+        }
     }
 }