Java Program to Calculate Average of Numbers Using Arrays

Calculating the average of numbers is a basic yet essential operation in programming. In Java, arrays offer a convenient way to store and manipulate a collection of data. In this article, we will explore various ways to calculate the average of numbers using arrays in Java.

What is an Average?

The average (or arithmetic mean) is calculated by summing all the elements and dividing by the number of elements.

Formula:

average = (sum of elements) / (total number of elements)

Approach 1: Using a for Loop (Static Input)

This is the most basic and widely used approach.

// Java code to calculate the average of numbers

public class AverageCalculator {
    public static void main(String[] args) {
        
        // Static array
        int[] arr = {10, 20, 30, 40, 50};
        int sum = 0;

        for (int i = 0; i < arr.length; i++) {
            sum += arr[i];
        }

        double average = (double) sum / arr.length;
        System.out.println("Average of Numbers: " + average);
    }
}

Output

Average of Numbers: 30.0

Explanation:

• We define a static array of integers.
• Use a for loop to calculate the sum.
• Compute the average by dividing sum by array length.

Approach 2: Using a for-each Loop

The enhanced for loop makes the code more readable and concise.

// Java code to calculate the average of numbers

public class AverageCalculator {
    public static void main(String[] args) {
        int[] arr = {15, 25, 35, 45, 55};
        int sum = 0;

        for (int num : arr) {
            sum += num;
        }

        double average = (double) sum / arr.length;
        System.out.println("Average of Numbers: " + average);
    }
}

Approach 3: Taking User Input Using Scanner

This is useful when the array size and elements are provided by the user at runtime.

// Java code to calculate the average of numbers

import java.util.Scanner;

public class AverageCalculator {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter Number of Elements: ");
        int n = scanner.nextInt();
        int[] arr = new int[n];

        int sum = 0;
        for (int i = 0; i < n; i++) {
            System.out.print("Enter " + (i+1) + " Element: ");
            arr[i] = scanner.nextInt();
            sum += arr[i];
        }

        double average = (double) sum / n;
        System.out.println("Average of Numbers: " + average);
        scanner.close();
    }
}

Approach 4: Using Java Streams (Java 8+)

Java 8 introduced the Stream API, which provides a functional way of computing averages.

// Java code to calculate the average of numbers

import java.util.Arrays;

public class AverageCalculator {
    public static void main(String[] args) {
        int[] arr = {10, 20, 30, 40, 50};

        double average = Arrays.stream(arr).average().orElse(Double.NaN); // Handles empty arrays

        System.out.println("Average of Numbers: " + average);
    }
}

Note:

• The average() method returns an OptionalDouble.
• Use orElse(Double.NaN) to handle the case of an empty array.

Approach 5: Using a Method for Reusability

Encapsulating logic into a method makes the code modular and reusable.

// Java code to calculate the average of numbers

public class AverageCalculator {

    public static double calculateAverage(int[] array) {
        int sum = 0;
        for (int num : array) {
            sum += num;
        }
        return (double) sum / array.length;
    }

    public static void main(String[] args) {
        int[] arr = {10, 20, 30, 40, 50};
        double avg = calculateAverage(arr);
        System.out.println("Average of Numbers: " + avg);
    }
}

Approach 6: Handling Edge Cases (Empty Arrays)

Always consider edge cases like:

• Empty arrays
• Arrays with one element
• Arrays with negative numbers or floating-point numbers

public class AverageCalculator {

    public static double calculateAverage(int[] array) {
        if (array == null || array.length == 0) {
            System.out.println("Array is empty or null.");
            return 0;
        }

        int sum = 0;
        for (int num : array) {
            sum += num;
        }
        return (double) sum / array.length;
    }

    public static void main(String[] args) {
        int[] numbers = {};
        double avg = calculateAverage(numbers);
        System.out.println("Average = " + avg);
    }
}