Remove the vowels from a string in Java

Understanding Vowel Removal

Vowel removal involves deleting all vowels (a, e, i, o, u) from a given string.

We will explore three different methods to remove vowels from a string using Java.

Method 1: Using a Loop

This method iterates through the string and constructs a new string without vowels.

public class RemoveVowels {
    public static String removeVowels(String str) {
        String result = "";
        for (char c : str.toCharArray()) {
            if ("aeiouAEIOU".indexOf(c) == -1) {
                result += c;
            }
        }
        return result;
    }

    public static void main(String[] args) {
        String str = "Hello World";
        System.out.println("String without vowels: " + removeVowels(str));
    }
}
            

Method 2: Using Recursion

This method removes vowels recursively.

public class RemoveVowelsRecursive {
    public static String removeVowelsRecursive(String str) {
        if (str.isEmpty()) return "";
        char first = str.charAt(0);
        String rest = removeVowelsRecursive(str.substring(1));
        return ("aeiouAEIOU".indexOf(first) == -1) ? first + rest : rest;
    }

    public static void main(String[] args) {
        String str = "Programming";
        System.out.println("String without vowels: " + removeVowelsRecursive(str));
    }
}
            

Method 3: Using StringBuilder

This method uses StringBuilder to remove vowels efficiently.

public class RemoveVowelsStringBuilder {
    public static String removeVowels(String str) {
        StringBuilder result = new StringBuilder();
        for (char c : str.toCharArray()) {
            if ("aeiouAEIOU".indexOf(c) == -1) {
                result.append(c);
            }
        }
        return result.toString();
    }

    public static void main(String[] args) {
        String str = "Count Vowels";
        System.out.println("String without vowels: " + removeVowels(str));
    }
}