FRQ Hacks • 2 min read

FRQ 3

a. Define an arrayList in Java. Explain its significance and usefulness in programming.

An ArrayList is a data structure that resembles a dynamic array and whose size can change dynamically when elements are added or removed. It is more flexible than arrays and is a component of the Java Collections Framework.

b. You need to implement a method calculateAverageGrade that takes an arrayList grades of integers representing student grades and returns the average of all the elements in the arrayList. Write the method signature and the method implementation. Include comments to explain your code.

import java.util.ArrayList;

public class GradeCalc {
    
    public static double calculateAverageGrade(ArrayList<Integer> grades) {
        int sum = 0;
        
        for (int grade : grades) { // iterate through the ArrayList to calculate the sum
            sum += grade;
        }
        
        double average = (double) sum / grades.size(); // divide sum by number of grades to get average
        
        return average;
    }

    public static void main(String[] args) {
        ArrayList<Integer> studentGrades = new ArrayList<>();
        studentGrades.add(10); // test data
        studentGrades.add(20);
        studentGrades.add(30);
        
        System.out.println("Average grade: " + calculateAverageGrade(studentGrades));
    }
}
GradeCalc.main(null);

Average grade: 20.0