..

src/CourseRegistrationStarter/Main.java

@@ -1,6 +1,7 @@
 package CourseRegistrationStarter;
 
-public class Main {
+public class Main
+{
     public static void main(String[] args) {
         // TODO:
         // 1. Create at least 3 courses
@@ -10,5 +11,21 @@ public class Main {
         // 5. Register the student in some courses
         // 6. Drop one course
         // 7. Print the final registered course list
-    }
+
+    Course calculus = new Course("Calculus", "MATH101", 30);
+    Course combination = new Course("Combination", "MATH102", 25);
+    Course AP = new Course("AP Computer Science", "CS201", 20);
+
+    Student mobina = new Student("Mobina", "404222");
+
+    RegistrationSystem system = new RegistrationSystem();
+
+    system.addCourseToSystem(calculus);
+    system.addCourseToSystem(combination);
+    system.addCourseToSystem(AP);
+    mobina.addCourse(AP);
+    mobina.addCourse(calculus);
+    mobina.dropCourse(calculus);
+    mobina.showRegisteredCourses();
 }
+}

src/CourseRegistrationStarter/RegistrationSystem.java

@@ -10,15 +10,24 @@ 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(int i=0; i<courses.size(); i++){
+            if (((courses.get(i)).getCourseCode()).equals(code))
+                return courses.get(i);
+        }
         return null;
     }
 
     public void showAllCourses() {
         // TODO: Print all courses in the system
+        for (int i = 0; i < courses.size(); i++) {
+        System.out.println(courses.get(i).getCourseName());
+    }
     }
 }

src/CourseRegistrationStarter/Student.java

@@ -23,17 +23,34 @@ 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
-        return false;
+
+        if (c.reduceCapacity())
+            registeredCourses.add(c);
+            return true;
+        else
+            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
+ 
+        for(int i=0; i<registeredCourses.size(); i++){
+           if (c.getCourseName().equals(registeredCourses.get(i).getCourseName())){
+               registeredCourses.remove(i);
+               c.increaseCapacity();
+               return true;
+           }
+        }
         return false;
     }
 
     public void showRegisteredCourses() {
         // TODO: Print all registered courses
+        for (int i=0; i<registeredCourses.size(); i++)
+        {
+            System.out.println(registeredCourses.get(i).getCourseName());
+        }
     }
 }