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

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:
+        Course AdvancedProgramming = new Course("Advanced Programming", "AP1404", 2);
-        // 1. Create at least 3 courses
+        Course DataStructures = new Course("Data Structures", "DS2201", 1);
-        // 2. Create 1 student
+        Course DatabaseSystems = new Course("Database Systems", "DB3301", 3);
-        // 3. Create a registration system
+
-        // 4. Add courses to the system
+        Student Zahra = new Student("Zahra", "404222093");
-        // 5. Register the student in some courses
+
-        // 6. Drop one course
+        RegistrationSystem TestSystem = new RegistrationSystem();
-        // 7. Print the final registered course list
+
+        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/Student.java

@@ -21,10 +21,9 @@ public class Student {
     }
 
     public boolean addCourse(Course c) {
-        if ((registeredCourses.size() < 3)&&(!(registeredCourses.contains(c))&&(c.getCapacity() > 0))) {
+        if ((registeredCourses.size() < 3) && (!(registeredCourses.contains(c)) && (c.getCapacity() > 0))) {
             registeredCourses.add(c);
-        }
+        } else if (registeredCourses.size() >= 3)
-        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!");
@@ -32,18 +31,21 @@ public class Student {
     }
 
     public boolean dropCourse(Course c) {
-        registeredCourses.remove(c);
+        if (registeredCourses.contains(c)) {
-        int temp = c.getCapacity();
+            registeredCourses.remove(c);
-        c.increaseCapacity();
+            c.increaseCapacity();
-        if ((temp > c.getCapacity())&&(!(registeredCourses.contains(c))))
             return true;
+        }
         return false;
     }
 
     public void showRegisteredCourses() {
-        for (Course i : registeredCourses)
+        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());
         }
     }