Calculate average of doubles using Lambda expression in Java

Java Lambda Program: Exercise-6 with Solution

Write a Java program to implement a lambda expression to find the average of a list of doubles.

Sample Solution:

Java Code:

import java.util.Arrays;
import java.util.List;

public class Main {
    public static void main(String[] args) {
        // Create a list of doubles
        List<Double> nums = Arrays.asList(3.5, 7.5, 4.3, 4.7, 5.1);
		// Print the list elements
        System.out.println("Original values: " + nums);

        // Calculate the average of the list using lambda expression
        double average = nums.stream()
                .mapToDouble(Double::doubleValue)
                .average()
                .orElse(0.0);

        // Print the average
        System.out.println("\nAverage of the original values: " + average);
    }
}

Sample Output:

Original values: [3.5, 7.5, 4.3, 4.7, 5.1]

Average of the original values: 5.0200000000000005

Explanation:

To calculate the average of the list, we use the stream() method on the nums list to convert it into a stream. Then, we use the mapToDouble() method to convert each Double object to its corresponding primitive double value. This step is necessary because the average() method operates on primitive double values.

Next, we call the average() method to calculate the average of the stream. If the stream is empty, we use orElse(0.0) to provide a default value of 0.0.

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