src/CourseRegistrationStarter/Main.java

@@ -2,13 +2,25 @@ 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("AdvancedProgramming", "AP1404", 2);
+        Course DataStructures = new Course("DataStructures", "DS2201", 1);
+        Course DatabaseSystems = new Course("DatabaseSystems", "DB3301", 3);
+
+        Student fateme = new Student("fateme", "404222000", 10);
+
+        RegistrationSystem A = new RegistrationSystem();
+
+        A.addCourseToSystem(AdvancedProgramming);
+        A.addCourseToSystem(DataStructures);
+        A.addCourseToSystem(DatabaseSystems);
+
+        fateme.addCourse(AdvancedProgramming);
+        fateme.addCourse(DataStructures);
+        fateme.addCourse(DatabaseSystems);
+
+        fateme.dropCourse(DataStructures);
+
+        fateme.showRegisteredCourses();
     }
 }

src/CourseRegistrationStarter/RegistrationSystem.java

@@ -9,16 +9,46 @@ public class RegistrationSystem {
     }
 
     public void addCourseToSystem(Course c) {
-        // TODO: Add the course to the system
+
+        for (int i=0 ; i < courses.size() ; i++) {
+
+            if(courses.get(i).getCourseCode().equals(c.getCourseCode()) ||
+                    courses.get(i).getCourseName().equals(c.getCourseName())) {
+
+                System.out.println("Course name or code already exists.");
+                return;
+            }
+        }
+
+        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 Course findCourseByName(String name) {
+
+        for(int i=0 ; i<courses.size() ; i++) {
+            if(courses.get(i).getCourseName().equals(name))
+                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.print("Course");
+            System.out.print(i+1);
+            System.out.print(" : " + courses.get(i).getCourseName() + "  " + courses.get(i).getCourseCode());
+            System.out.println(", capacity : " + courses.get(i).getCapacity());
+        }
     }
 }

src/CourseRegistrationStarter/Student.java

@@ -2,14 +2,16 @@ package CourseRegistrationStarter;
 import java.util.ArrayList;
 
 public class Student {
-    private String name;
-    private String studentId;
+    private final String name;
+    private final String studentId;
     private ArrayList<Course> registeredCourses;
+    private int courseLimit;
 
-    public Student(String name, String studentId) {
+    public Student(String name, String studentId, int courseLimit) {
         this.name = name;
         this.studentId = studentId;
         this.registeredCourses = new ArrayList<>();
+        this.courseLimit = courseLimit;
     }
 
     public String getName() {
@@ -21,19 +23,35 @@ 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(c.getCapacity() > 0 && registeredCourses.size() < courseLimit) {
+            registeredCourses.add(c);
+            c.reduceCapacity();
+            return true;
+        }
         return false;
     }
 
+    public void setCourseLimit(int amount) {
+        if(amount>0)
+            courseLimit = amount;
+    }
+
     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(int i=0 ; i < registeredCourses.size() ; i++) {
+            System.out.print("Course");
+            System.out.print(i+1);
+            System.out.print(" : " + registeredCourses.get(i).getCourseName() + "  " + registeredCourses.get(i).getCourseCode());
+            System.out.println(", capacity : " +registeredCourses.get(i).getCapacity());
+        }
     }
 }