code and setup

src/main/java/models/Course.java

@@ -0,0 +1,67 @@
+package models;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Course {
+    private static int nextId = 1;
+
+    private int id;
+    private String name;
+    private Teacher teacher;
+    private List<Student> students;
+
+    public Course(String name) {
+        this.id = nextId++;
+        this.name = name;
+        this.students = new ArrayList<>();
+    }
+
+    public int getId() { return id; }
+    public String getName() { return name; }
+    public Teacher getTeacher() { return teacher; }
+
+    public void setTeacher(Teacher teacher) {
+        this.teacher = teacher;
+    }
+
+    public boolean addStudent(Student student) {
+        if (students.contains(student)) {
+            return false;
+        }
+        students.add(student);
+        return true;
+    }
+
+    public List<Student> getStudents() {
+        return students;  // ساده، بدون unmodifiable
+    }
+
+    public void showStudents() {
+        if (students.isEmpty()) {
+            System.out.println("  No students enrolled yet.");
+        } else {
+            System.out.println("  Students in " + name + ":");
+            for (Student s : students) {
+                System.out.println("    - " + s.getUsername());
+            }
+        }
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null || getClass() != obj.getClass()) return false;
+        Course course = (Course) obj;
+        return id == course.id;
+    }
+
+    @Override
+    public String toString() {
+        if (teacher != null) {
+            return "[ID:" + id + "] " + name + " (Teacher: " + teacher.getUsername() + ")";
+        } else {
+            return "[ID:" + id + "] " + name + " (No teacher assigned)";
+        }
+    }
+}

src/main/java/models/Student.java

@@ -0,0 +1,15 @@
+package models;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Student extends User {
+    private List<Course> enrolledCourses;
+
+    public Student(String username, String password) {
+        super(username, password);
+        this.enrolledCourses = new ArrayList<>();
+    }
+    //TODO(complete the student class)
+
+}

src/main/java/models/Teacher.java

@@ -0,0 +1,53 @@
+package models;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Teacher extends User {
+    private List<Course> myCourses;
+
+    public Teacher(String username, String password) {
+        super(username, password);
+        this.myCourses = new ArrayList<>();
+    }
+
+    public boolean addCourse(Course course) {
+        if (myCourses.contains(course)) {
+            return false;
+        }
+        myCourses.add(course);
+        course.setTeacher(this);
+        return true;
+    }
+
+    public boolean removeCourse(Course course) {
+        if (myCourses.remove(course)) {
+            course.setTeacher(null);
+            return true;
+        }
+        return false;
+    }
+
+    public List<Course> getMyCourses() {
+        return myCourses;
+    }
+
+    public void showMyCourses() {
+        if (myCourses.isEmpty()) {
+            System.out.println(" You don't teach any course yet.");
+        } else {
+            System.out.println("\n My Courses:");
+            for (int i = 0; i < myCourses.size(); i++) {
+                System.out.println("  " + (i+1) + ". " + myCourses.get(i));
+            }
+        }
+    }
+
+    public void showStudentsInCourse(Course course) {
+        if (!myCourses.contains(course)) {
+            System.out.println(" You don't teach this course!");
+            return;
+        }
+        course.showStudents();
+    }
+}

src/main/java/models/User.java

@@ -0,0 +1,42 @@
+package models;
+
+public abstract class User {
+    protected String username;
+    protected String password;  // ساده نگه می‌داریم برای سطح مقدماتی
+
+    public User(String username, String password) {
+        this.username = username;
+        this.password = password;
+    }
+
+    public String getUsername() { return username; }
+
+    public boolean checkPassword(String password) {
+        return this.password.equals(password);
+    }
+
+    public static String validateUsername(String username) {
+        if (username == null || username.trim().isEmpty()) {
+            return "Username cannot be empty!";
+        }
+        if (username.length() < 3) {
+            return "Username must be at least 3 characters!";
+        }
+        return null;
+    }
+
+    public static String validatePassword(String password) {
+        if (password == null || password.length() < 4) {
+            return "Password must be at least 4 characters!";
+        }
+        return null;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) return true;
+        if (obj == null || getClass() != obj.getClass()) return false;
+        User user = (User) obj;
+        return username.equalsIgnoreCase(user.username);
+    }
+}