The main class is completed, the project and all the bonuses are completed.

.idea/.name

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

src/ClassExamples/Example01.java

@@ -1,9 +1,10 @@
 package ClassExamples;
+import CourseRegistrationStarter.Course;
 
 public class Example01
 {
     public static void main(String[] args)
     {
-        System.out.println("Hi!");
+        Course Advanced_Programming = new Course("AdvancedProgramming", "AP1404", 2);
     }
 }

src/CourseRegistrationStarter/Main.java

@@ -2,13 +2,28 @@ 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 AdvancedProgramming = new Course("Advanced Programming", "AP1404", 2);
+        Course DataStructures = new Course("Data Structures", "DS2201", 1);
+        Course DatabaseSystems = new Course("Database Systems", "DB3301", 3);
+
+        Student Zahra = new Student("Zahra", "404222093");
+
+        RegistrationSystem TestSystem = new RegistrationSystem();
+
+        TestSystem.addCourseToSystem(AdvancedProgramming);
+        TestSystem.addCourseToSystem(DataStructures);
+        TestSystem.addCourseToSystem(DatabaseSystems);
+
+        System.out.print("Adding Advanced Programming: ");
+        System.out.println(Zahra.addCourse(AdvancedProgramming));
+        System.out.print("Adding Data Structures: ");
+        System.out.println(Zahra.addCourse(DataStructures));
+        System.out.print("Adding Database Systems: ");
+        System.out.println(Zahra.addCourse(DatabaseSystems));
+
+        System.out.print("Dropping Data Structures: ");
+        System.out.println(Zahra.dropCourse(DataStructures));
+
+        Zahra.showRegisteredCourses();
     }
 }

src/CourseRegistrationStarter/RegistrationSystem.java

@@ -1,5 +1,6 @@
 package CourseRegistrationStarter;
 import java.util.ArrayList;
+import java.util.Scanner;
 
 public class RegistrationSystem {
     private ArrayList<Course> courses;
@@ -9,16 +10,37 @@ 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 i : courses)
+        {
+            if (i.getCourseCode().equals(code))
+            {
+                return i;
+            }
+        }
+        return null;
+    }
+
+    public Course findCourseByName(String name) {
+        for (Course i : courses)
+        {
+            if (i.getCourseCode().equals(name))
+            {
+                return i;
+            }
+        }
         return null;
     }
 
     public void showAllCourses() {
-        // TODO: Print all courses in the system
+        for (Course i : courses)
+        {
+            System.out.println(i.getCourseName());
+            System.out.println(i.getCourseCode());
+            System.out.println(i.getCapacity());
+        }
     }
-}
+}

src/CourseRegistrationStarter/Student.java

@@ -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
-        return false;
+        if ((registeredCourses.size() < 3) && (!(registeredCourses.contains(c)) && (c.getCapacity() > 0))) {
+            registeredCourses.add(c);
+        } else if (registeredCourses.size() >= 3)
+            System.out.println("You can only attend 3 courses!");
+        else if (registeredCourses.contains(c))
+            System.out.println("You can't register twice!");
+        return c.reduceCapacity();
     }
 
     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.contains(c)) {
+            registeredCourses.remove(c);
+            c.increaseCapacity();
+            return true;
+        }
         return false;
     }
 
     public void showRegisteredCourses() {
-        // TODO: Print all registered courses
+        System.out.println("_________________________________");
+        System.out.println("You participate in:");
+        for (Course i : registeredCourses) {
+            System.out.println("=======================");
+            System.out.println(i.getCourseName());
+            System.out.print("Class ID: ");
+            System.out.println(i.getCourseCode());
+        }
     }
 }