adding second part

src/com/university/Course.java

@@ -44,7 +44,8 @@ public class Course {
     }
 
     public void enrollStudent(Student student){
-        stds.add(student);
+        if(student.getDepartment() == this.dpart){
+        stds.add(student);}
 
     }
 

src/com/university/Department.java

 package com.university;
 
+import java.util.ArrayList;
+
 public class Department {
     private String name;
+    private ArrayList<Student> stds = new ArrayList<Student>();
+    private Student[] students;
+    private ArrayList<Course> crs = new ArrayList<Course>();
+    private Course[] courses;
+    private ArrayList<Professor> prfs = new ArrayList<Professor>();
+    private Professor[] professors;
     public Department(String name) {
         this.name = name;
     }
@@ -11,38 +19,61 @@ public class Department {
     }
 
     public void addStudent(Student student){
+        if(student.getDepartment().getName() == this.name){
+            stds.add(student);
+        }
 
     }
 
     public Student[] getStudents(){
-        return null;
+        students = stds.toArray(new Student[stds.size()]);
+        return students;
     }
 
     public void removeStudent(Student student){
+        if(student.getDepartment().getName() == this.name){
+            for(Student std : students){
+                if(std == student)
+                stds.remove(student);}
+        }
 
     }
 
     public void addCourse(Course course){
+        if(course.getDepartment().getName() == this.name) {
+            crs.add(course);
+        }
 
     }
 
     public Course[] getCourses(){
-        return null;
+        courses = crs.toArray(new Course[crs.size()]);
+        return courses;
     }
 
     public void removeCourse(Course course){
+        crs.remove(course);
 
     }
 
-    public void addProfessor(Professor student){
+    public void addProfessor(Professor professor){
+        if(professor.getDepartment().getName() == this.name){
+            prfs.add(professor);
+        }
 
     }
 
     public Professor[] getProfessors(){
-        return null;
+        professors = prfs.toArray(new Professor[prfs.size()]);
+        return professors;
     }
 
     public void removeProfessor(Professor professor){
+        for(Professor pfs : prfs){
+            if(pfs == professor){
+                prfs.remove(professor);
+            }
+        }
 
     }
 

src/test/CourseTest.java

+package test;
+
+import com.university.Student;
+import com.university.Course;
+import com.university.Professor;
+import com.university.Department;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import static junit.framework.TestCase.assertEquals;
+import static junit.framework.TestCase.assertNotNull;
+import static org.junit.Assert.assertNotEquals;
+
+public class CourseTest {
+    static Course course;
+
+    @BeforeAll
+
+    public static void createCourse(){
+        Department department = new Department("Computer");
+        Department department1 = new Department("Civil");
+        Professor professor = new Professor(department , "HajMohammadi");
+        course = new Course("2122" , "EnteghaleHararat" ,  department , professor  , 21);
+        Student std1 = new Student("Mohammad" , "9525080" , "Omran" , department1);
+        course.enrollStudent(std1);
+        Student std2 = new Student("Karim" , "9321098" , "Electricity" , department);
+        course.enrollStudent(std2);
+        Student std3 = new Student("ali" , "9321088" , "Electricity" , department);
+        course.enrollStudent(std3);
+        Student std4 = new Student("reza" , "9321078" , "Electricity" , department);
+        course.enrollStudent(std4);
+        Student std5 = new Student("farzin" , "9321098" , "Electricity" , department);
+        course.enrollStudent(std5);
+        Student std6 = new Student("hossein" , "9321098" , "Electricity" , department);
+        course.enrollStudent(std6);
+        Student std7 = new Student("nima" , "9321098" , "Electricity" , department);
+        course.enrollStudent(std7);
+        Student std8= new Student("erfan" , "9321098" , "Electricity" , department);
+        course.enrollStudent(std8);
+        Student std9 = new Student("javad" , "9321098" , "Electricity" , department);
+        course.enrollStudent(std9);
+        Student std10 = new Student("arman" , "9321098" , "Electricity" , department);
+        course.enrollStudent(std10);
+        Student[] stds = new Student[]{std1 , std2 , std3 ,std4 , std5 , std6 , std7 , std8 , std9 , std10};
+    }
+
+    @Test
+    public void testCourseGetID(){
+        assertNotNull(course.getID());
+    }
+    @Test
+    public void testCourseGetDepartment(){
+        assertNotNull(course.getDepartment());
+    }
+    @Test
+    public void testCourseGetName(){
+        assertNotNull(course.getName());
+    }
+    @Test
+    public void testCourseGetProfessor(){
+        assertNotNull(course.getProfessor());
+    }
+    @Test
+    public void testCourseGetEnrollStudents(){
+        assertNotEquals(1 , course.getStudents().length);
+    }
+    @Test
+    public void testCourseEnrollStudents(){
+        for(Student std : stds){
+
+        }
+    }
+}

src/test/DepartmentTest.java

+package test;
+
+import com.university.Student;
+import com.university.Professor;
+import com.university.Department;
+import com.university.Course;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import static junit.framework.TestCase.assertEquals;
+import static junit.framework.TestCase.assertNotNull;
+import static org.junit.Assert.assertNotEquals;
+
+public class DepartmentTest {
+    static Department department;
+
+    @BeforeAll
+    public static void CreateDepartment(){
+        department = new Department("Computer");
+        Student student = new Student("Ali" , "3212" , "Computer" , department);
+
+    }
+}