Calculate the Sum and Average of Elements in an ArrayList in Java

A Dynamic and Adaptable method for storing and managing collections of elements is to use ArrayList. Finding the total and average of an ArrayList’s items is frequently required when working with numerical data that is stored in the list.

In this article, we will see how we can sum and find the average of the ArrayList in Java.

Methods to Calculate the Sum or Average of Elements in an ArrayList

• Using Enhanced for loop
• Using simple for-loop

Program to Calculate the Sum and Average of Elements in an ArrayList in Java

Method 1: Using Enhanced for loop

The following implementation demonstrates how to Sum and find the Average of an ArrayList using for each loop.

Java

// Java program to calculate sum and average of elements in an ArrayList
import java.io.*;
import java.util.ArrayList;

class GFG {
    public static void main(String[] args)
    {
        ArrayList<Integer> list = new ArrayList<>();
        list.add(10);
        list.add(20);
        list.add(30);
        list.add(45);
        list.add(54);

        // Calculate the sum of elements
        int sum = 0;
        for (int num : list) {
            sum += num;
        }
        System.out.println("Sum: " + sum);

        // Calculate the average of elements
        double average = (double)sum / list.size();
        System.out.println("Average: " + average);
    }
}

Output

Sum: 159
Average: 31.8

Explanation of the Program:

• In the above program, an ArrayList named list is created to store integers.
• Integer values are added to the ArrayList.
• The Sum is calculated using an enhanced for loop (for-each loop), where each element is iterated and added to the sum variable.
• Then, the average of elements is calculated by dividing the sum by the number of elements in the list, converted to double to get a more accurate result.
• Finally, the sum and average are printed to the console.

Method 2: Using for loop

The following implementation demonstrates how to Sum and find Average of an ArrayList using simple for loop.

Java

// Java program to calculate sum and average of elements in an ArrayList
import java.io.*;
import java.util.ArrayList;

class Main {
    public static void main(String[] args)
    {
        ArrayList<Integer> list = new ArrayList<>();
        list.add(10);
        list.add(20);
        list.add(30);
        list.add(45);
        list.add(54);

        // Calculate the sum of elements
        int sum = 0;
        for (int i = 0; i < list.size(); i++)
        {
            sum += list.get(i);
        }
        System.out.println("Sum: " + sum);

        // Calculate the average of elements
        double average = (double)sum / list.size();
        System.out.println("Average: " + average);
    }
}

Output

Sum: 159
Average: 31.8

Explanation of the Program:

• In the above program, an ArrayList named list is created to store integers.
• Integer values are added to the ArrayList.
• The Sum is calculated by iterating through the list and adding each element to the sum variable.
• Then, the average of elements is calculated by dividing the sum by the number of elements in the list, converted to double to get a more accurate result.
• Finally, the sum and average are printed to the console.