StudentManager.java

// Business Logic Layer
import java.util.ArrayList;

public class StudentManager {

    private ArrayList<Student> students;

    // Constructor
    public StudentManager(){
        students = new ArrayList<>();
    }

    // CRUD operations
    public void addStudent(Student student){
        students.add(student);
        System.out.println("Student added successfully");
    }

    public void viewStudents(){
        if(students.isEmpty()){
            System.out.println("No Students found");
            return;
        }
        for(Student student: students){
            System.out.println(student);
        }
    }

    // Linear Search O(n)
    public Student searchStudentById(int id){
        for (Student student : students){
            if(student.getId() == id){
                return student;
            }
        }
        return null;
    }

    public void deleteStudent(int id){
        Student student = searchStudentById(id);

        if (student == null){
            System.out.println("Student Not Found");
            return;
        }

        students.remove(student); // O(n)
        System.out.println("Student deleted successfully");
    }

    public void updateStudent(int id, String newName, int newAge, String newCourse){

        Student student = searchStudentById(id);

        if(student == null){
            System.out.println("Student not found");
            return;
        }
        student.setName(newName);
        student.setAge(newAge);
        student.setCourse(newCourse);

        System.out.println("Student updated successfully");
    }
}