1/*2 * RemoveVowels.java3 *4 * Computer Science S-225 *6 * A class that contains a recursive method for removing all7 * lower-case vowels that appear in a string.8 */9 10public class RemoveVowels {11 /*12 * removeVowels - a recursive method that returns 13 * string formed by removing all lower-case vowels14 * (a, e, i, o, u) from the String str.15 */16 public static String removeVowels(String str) {17 // base cases18 if (str == null) {19 return null;20 } else if (str.equals("")) {21 return "";22 } else {23 // recursive case24 25 // Make a recursive call to remove vowels from the26 // rest of the string.27 String removedFromRest = removeVowels(str.substring(1));28 29 // If the first character in str is a vowel,30 // we don't include it in the return value.31 // If it isn't a vowel, we do include it.32 char first = str.charAt(0);33 if (first == 'a' || first == 'e' || first == 'i' ||34 first == 'o' || first == 'u') {35 return removedFromRest;36 } else {37 return first + removedFromRest;38 }39 }40 }41}