Count Vowels in a String in Java — Definition, Examples and Program

Count Vowels in a String in Java — Definition, Examples and Program

Counting vowels in a string is a basic string problem that helps beginners understand character comparison, loops, and conditional statements.

In this blog, you will learn:

• What vowels are
• How to count vowels in a string
• Step-by-step examples
• A simple Java program
• Practice challenges

What Are Vowels?

Vowels in the English alphabet are:

a, e, i, o, u

Both uppercase and lowercase vowels should be considered while counting.

How the Logic Works

To count vowels in a string:

1. Read the string from the user.
2. Traverse each character of the string.
3. Check if the character is a vowel.
4. Increase the count when a vowel is found.

Example 1

Input: "programming"

• p → not a vowel
• r → not a vowel
• o → vowel (count = 1)
• a → vowel (count = 2)
• i → vowel (count = 3)

Total Vowels: 3

Example 2

Input: "HELLO WORLD"

• E → vowel
• O → vowel
• O → vowel

Total Vowels: 3

Java Program to Count Vowels

import java.util.Scanner;

public class CountVowels {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        System.out.print("Enter a string: ");
        String input = sc.nextLine();

        int vowelCount = 0;

        input = input.toLowerCase();

        for (int i = 0; i < input.length(); i++) {
            char ch = input.charAt(i);

            if (ch == 'a' || ch == 'e' || ch == 'i' ||
                ch == 'o' || ch == 'u') {
                vowelCount++;
            }
        }

        System.out.println("Number of vowels: " + vowelCount);
    }
}

Sample Output

Enter a string: Education
Number of vowels: 5

Practice Challenges

1. Modify the program to count consonants as well.
2. Count vowels without converting the string to lowercase.
3. Find which vowel appears the most times in a string.

Counting vowels is a simple yet powerful exercise that strengthens your understanding of strings and conditions in Java.