Example: Count Vowels and Consonants - Java 8 Streams in Java

// Count Vowels and Consonants - Java 8 Streams
import java.util.Scanner;

// Main class containing the entry point of the program
public class Main {
    public static void main(String[] args) {
        // Step 1: Initialize Scanner and get input string
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter a string: ");
        String inputString = scanner.nextLine();
        scanner.close();

        // Step 2: Convert the string to lowercase for easier comparison
        String lowerCaseString = inputString.toLowerCase();

        // Step 3: Define a string of vowels for quick lookup
        String vowels = "aeiou";

        // Step 4: Count vowels using streams
        long vowelCount = lowerCaseString.chars()             // Get an IntStream of character codes
                                         .filter(c -> Character.isLetter(c)) // Filter for alphabetic characters
                                         .filter(c -> vowels.indexOf(c) != -1) // Filter for characters present in 'vowels' string
                                         .count();                            // Count the remaining characters

        // Step 5: Count consonants using streams
        long consonantCount = lowerCaseString.chars()         // Get an IntStream of character codes
                                             .filter(c -> Character.isLetter(c)) // Filter for alphabetic characters
                                             .filter(c -> vowels.indexOf(c) == -1) // Filter for characters NOT present in 'vowels' string
                                             .count();                            // Count the remaining characters

        // Step 6: Print the results
        System.out.println("Vowels: " + vowelCount);
        System.out.println("Consonants: " + consonantCount);
    }
}