StudGradeManager.java

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

public class StudGradeManager {
    public static void main(String[] args){
        ArrayList<Student> students = new ArrayList<>();
        Scanner sc = new Scanner(System.in);
        //MENU FOR USER TO SELECT WHICH OPERATION TO PERFORM
        while(true){
            System.out.println("\nStudent Grade Manager");
            System.out.println("1. Add Student");
            System.out.println("2. View Students");
            System.out.println("3. Calculate Average");
            System.out.println("4. Exit");
            System.out.print("Enter your choice:");

            int choice = sc.nextInt();

            switch(choice){

                case 1:
                sc.nextLine();

                System.out.println("Enter Student name: ");
                String name = sc.nextLine();

                System.out.println("Enter roll number: ");
                int rollNo = sc.nextInt();

                System.out.println("Enter grade: ");
                double grade = sc.nextDouble();

                Student s = new Student(name,rollNo,grade);
                students.add(s);

                System.out.println("Student added successfully!");
                break;

                case 2:
    if(students.size() == 0){
        System.out.println("No students added yet.");
    } else {

        System.out.println("\nStudent List:");

        for(int i = 0; i < students.size(); i++){
            Student student = students.get(i);

            System.out.println(
                "Name: " + student.name +
                ", Roll No: " + student.rollNo +
                ", Grade: " + student.grade
            );
        }
    }
    break;

                case 3:
                    if(students.size() == 0){
                        System.out.println("No students available to calculate average.");
                    }else{
                        double sum = 0;

                        for(int i = 0;i<students.size();i++){
                            sum+=students.get(i).grade;
                        }

                        double average = sum / students.size();

                        System.out.println("Average grade: " + average);
                    }
                break;

                case 4:
                System.out.println("Exiting program...");
                sc.close();
                return;

                default:
                    System.out.println("Invalid choice");

                
            }
        }

    }
    
}

class Student {
    String name;
    int rollNo;
    double grade;

    Student(String name,int rollNo,double grade){
    this.name = name;
    this.rollNo = rollNo;
    this.grade = grade;
}
}