Java Program: Lambda expression to find average string length

Java Lambda Program: Exercise-23 with Solution

Write a Java program to implement a lambda expression to find the average length of strings in a list.

Sample Solution:

Java Code:

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

public class Main {
  public static void main(String[] args) {
    List <String> colors = Arrays.asList("Red", "Black", "White", "Orange", "Blue");
    System.out.println("List of colors: " + colors);

    double averageLength = calculateAverageLength(colors);
    System.out.println("Average length of colors(strings): " + averageLength);

  public static double calculateAverageLength(List < String > strings) {
    return strings.stream()
      .mapToInt(String::length) // Convert each string to its length
      .average() // Calculate the average
      .orElse(0); // If the list is empty, return 0 as the default value

Sample Output:

List of colors: [Red, Black, White, Orange, Blue]
Average length of colors(strings): 4.6


In the above exercise,

The main() method creates a list of strings (strings) containing four elements.

Following are the steps taken by the calculateAverageLength method when given a list of strings:

  • The stream() method is used on the strings list to create a stream of strings.
  • The mapToInt method converts each string to its length by using a method reference String::length.
  • The average method calculates the average length of the strings in the stream.
  • The orElse method is used to provide a default value of 0 if the list is empty.

The calculated average length is returned by the calculateAverageLength method and stored in the averageLength variable.


Flowchart: Java  Exercises: Sort list of objects with lambda expression.

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Java Lambda Exercises Previous: Lambda expression for checking uppercase, lowercase, or mixedcase strings.
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