StudentGradeManager.java

import java.util.*;
class Student {
    String name;
    ArrayList<Double> grades;
    Student(String name) {
        this.name = name;
        this.grades = new ArrayList<>();
    }

    void addGrade(double grade) {
        grades.add(grade);
    }

    double average() {
        double sum = 0;
        for (double g : grades) sum += g;
        return grades.size() == 0 ? 0 : sum / grades.size();
    }

    double highest() {
        return Collections.max(grades);
    }

    double lowest() {
        return Collections.min(grades);
    }
}
public class StudentGradeManager {
    static ArrayList<Student> students = new ArrayList<>();
    static Scanner sc = new Scanner(System.in);
    public static void main(String[] args) {
        while (true) {
            System.out.println("1 Add Student");
            System.out.println("2 Add Grade");
            System.out.println("3 View Report");
            System.out.println("4 Exit");

            int choice = sc.nextInt();
            sc.nextLine();

            if (choice == 1) addStudent();
            else if (choice == 2) addGrade();
            else if (choice == 3) report();
            else break;
        }
    }

    static void addStudent() {
        String name = sc.nextLine();
        students.add(new Student(name));
    }
    static void addGrade() {
        String name = sc.nextLine();
        double grade = sc.nextDouble();

        for (Student s : students) {
            if (s.name.equalsIgnoreCase(name)) {
                s.addGrade(grade);
                return;
            }
        }
    }

    static void report() {
        for (Student s : students) {
            if (s.grades.size() == 0) continue;
            System.out.println(s.name + " Avg: " + s.average() + " High: " + s.highest() + " Low: " + s.lowest());
        }
    }
}