Java Program to Count Vowels and Consonants in a String

In this article, we'll introduce beginners to a Java program that counts the number of vowels and consonants in a given string. 

Basic Concept

English vowels are: A, E, I, O, U (and their lowercase counterparts). Every other letter of the alphabet is typically considered a consonant. By analyzing each character of a string, we can categorize them as vowels or consonants.

Java Program to Count Vowels and Consonants in a String

import java.util.Scanner;

public class VowelConsonantCounter {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter your string:");
        String input = scanner.nextLine();

        int[] counts = countVowelsAndConsonants(input);

        System.out.println("Number of vowels: " + counts[0]);
        System.out.println("Number of consonants: " + counts[1]);
    }

    public static int[] countVowelsAndConsonants(String input) {
        int vowelsCount = 0, consonantsCount = 0;

        for (char c : input.toLowerCase().toCharArray()) {
            if (c >= 'a' && c <= 'z') { // Ensure character is a letter
                if ("aeiou".indexOf(c) != -1) {
                    vowelsCount++;
                } else {
                    consonantsCount++;
                }
            }
        }

        return new int[]{vowelsCount, consonantsCount};
    }
}

Output:

Enter your string:
Hello World
Number of vowels: 3
Number of consonants: 7

Step by Step Explanation: 

Taking User Input: 

        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter your string:");
        String input = scanner.nextLine();

We initiate the Scanner class to collect a string input from the user. 

Analyzing Each Character:

for (char c : input.toLowerCase().toCharArray()) {

We convert the entire string to lowercase to make the comparison case-insensitive and then convert the string to a character array. Now, we can easily loop through each character. 

Checking if a Character is a Letter: 

if (c >= 'a' && c <= 'z') {

Before categorizing a character as a vowel or consonant, we ensure it's a letter of the alphabet.

Identifying Vowels and Consonants:

if ("aeiou".indexOf(c) != -1) {
    vowelsCount++;
} else {
    consonantsCount++;
}

For each character, if it's found in the string "aeiou", then it's a vowel; otherwise, it's a consonant.

Displaying the Result: 

System.out.println("Number of vowels: " + counts[0]);
System.out.println("Number of consonants: " + counts[1]);

After processing the entire string, we display the total count of vowels and consonants.

Conclusion

By creating a program to count vowels and consonants, beginners not only practice string manipulation in Java but also gain exposure to conditional logic and loops. As you further progress on your coding journey, always remember that the foundational understanding you gain from simple exercises like this will be invaluable in building complex applications. Keep practicing and exploring!

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