StudentManagementSystem.java

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

class Student {
    private int id;
    private String name;
    private double marks;

    // Constructor
    public Student(int id, String name, double marks) {
        this.id = id;
        this.name = name;
        this.marks = marks;
    }

    // Getters & Setters
    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public double getMarks() {
        return marks;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setMarks(double marks) {
        this.marks = marks;
    }

    // Display student
    public void display() {
        System.out.println("ID: " + id + ", Name: " + name + ", Marks: " + marks);
    }
}

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

    public static void main(String[] args) {
        int choice;

        do {
            System.out.println("\n=== Student Record 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("5. Exit");
            System.out.print("Enter your choice: ");
            choice = sc.nextInt();

            switch (choice) {
                case 1 -> addStudent();
                case 2 -> viewStudents();
                case 3 -> updateStudent();
                case 4 -> deleteStudent();
                case 5 -> System.out.println("Exiting the system. Goodbye!");
                default -> System.out.println("Invalid choice. Try again.");
            }

        } while (choice != 5);
    }

    private static void addStudent() {
        System.out.print("Enter student ID: ");
        int id = sc.nextInt();
        sc.nextLine(); // consume newline

        System.out.print("Enter student name: ");
        String name = sc.nextLine();

        System.out.print("Enter student marks: ");
        double marks = sc.nextDouble();

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

    private static void viewStudents() {
        if (students.isEmpty()) {
            System.out.println("No student records available.");
        } else {
            System.out.println("\n--- Student Records ---");
            for (Student s : students) {
                s.display();
            }
        }
    }

    private static void updateStudent() {
        System.out.print("Enter student ID to update: ");
        int id = sc.nextInt();
        boolean found = false;

        for (Student s : students) {
            if (s.getId() == id) {
                sc.nextLine(); 
                System.out.print("Enter new name: ");
                String newName = sc.nextLine();
                System.out.print("Enter new marks: ");
                double newMarks = sc.nextDouble();

                s.setName(newName);
                s.setMarks(newMarks);
                System.out.println("Student record updated.");
                found = true;
                break;
            }
        }

        if (!found) {
            System.out.println("Student with ID " + id + " not found.");
        }
    }

    private static void deleteStudent() {
        System.out.print("Enter student ID to delete: ");
        int id = sc.nextInt();
        boolean removed = students.removeIf(s -> s.getId() == id);

        if (removed) {
            System.out.println("Student deleted successfully.");
        } else {
            System.out.println("Student with ID " + id + " not found.");
        }
    }
}