StudentManagementSystem.java

import java.util.ArrayList;
import java.util.Scanner;

public class StudentManagementSystem {
    private ArrayList<Student> students = new ArrayList<>();
    private Scanner scanner = new Scanner(System.in);

    // Add a new student
    public void addStudent() {
        System.out.print("Enter ID: ");
        int id = scanner.nextInt();
        scanner.nextLine(); 
        System.out.print("Enter Name: ");
        String name = scanner.nextLine();
        System.out.print("Enter Marks: ");
        double marks = scanner.nextDouble();

        students.add(new Student(id, name, marks));
        System.out.println("Student added successfully!");
    }

    // View all students
    public void viewStudents() {
        if (students.isEmpty()) {
            System.out.println("No students to display.");
            return;
        }
        System.out.println("\n--- Student List ---");
        for (Student s : students) {
            s.display();
        }
    }

    // Update student details
    public void updateStudent() {
        System.out.print("Enter Student ID to update: ");
        int id = scanner.nextInt();
        scanner.nextLine();

        for (Student s : students) {
            if (s.getId() == id) {
                System.out.print("Enter new name: ");
                s.setName(scanner.nextLine());
                System.out.print("Enter new marks: ");
                s.setMarks(scanner.nextDouble());
                System.out.println("Student updated successfully!");
                return;
            }
        }
        System.out.println("Student not found!");
    }

    // Delete student
    public void deleteStudent() {
        System.out.print("Enter Student ID to delete: ");
        int id = scanner.nextInt();

        for (Student s : students) {
            if (s.getId() == id) {
                students.remove(s);
                System.out.println("Student deleted successfully!");
                return;
            }
        }
        System.out.println("Student not found!");
    }

    // Menu loop
    public void menu() {
        int choice;
        do {
            System.out.println("\n=== Student Management System ===");
            System.out.println("1. Add Student");
            System.out.println("2. View Students");
            System.out.println("3. Update Student");
            System.out.println("4. Delete Student");
            System.out.println("0. Exit");
            System.out.print("Enter choice: ");
            choice = scanner.nextInt();

            switch (choice) {
                case 1: addStudent(); break;
                case 2: viewStudents(); break;
                case 3: updateStudent(); break;
                case 4: deleteStudent(); break;
                case 0: System.out.println("Exiting..."); break;
                default: System.out.println("Invalid choice! Try again.");
            }
        } while (choice != 0);
    }

    public static void main(String[] args) {
        StudentManagementSystem sms = new StudentManagementSystem();
        sms.menu();
    }
}