Task1.java

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

public class Task1 {
    public static void main(String[] args) {
        ArrayList<Double> grades = new ArrayList<>();
        Scanner scanner = new Scanner(System.in);
        String input;

        System.out.println("Enter student grades. Type 'done' to finish:");

        while (true) {
            System.out.print("Enter grade: ");
            input = scanner.nextLine();

            if (input.equalsIgnoreCase("done")) {
                break;
            }

            try {
                double grade = Double.parseDouble(input);
                if (grade < 0 || grade > 100) {
                    System.out.println("Please enter a grade between 0 and 100.");
                } else {
                    grades.add(grade);
                }
            } catch (NumberFormatException e) {
                System.out.println("Invalid input. Please enter a numeric value.");
            }
        }

        if (grades.isEmpty()) {
            System.out.println("No grades entered.");
        } else {
            double average = calculateAverage(grades);
            double highest = findHighest(grades);
            double lowest = findLowest(grades);

            System.out.println("\nGrade Summary:");
            System.out.println("Average Grade: " + average);
            System.out.println("Highest Grade: " + highest);
            System.out.println("Lowest Grade: " + lowest);
        }
// closing the scanner object to avoid leaks in the code
        scanner.close();
    }

    private static double calculateAverage(ArrayList<Double> grades) {
        double sum = 0;
        for (double grade : grades) {
            sum += grade;
        }
        return sum / grades.size();
    }

    private static double findHighest(ArrayList<Double> grades) {
        double highest = grades.get(0);
        for (double grade : grades) {
            if (grade > highest) {
                highest = grade;
            }
        }
        return highest;
    }

    private static double findLowest(ArrayList<Double> grades) {
        double lowest = grades.get(0);
        for (double grade : grades) {
            if (grade < lowest) {
                lowest = grade;
            }
        }
        return lowest;
    }
}