public static void main() {
    String turtles = convertToWhale("Normal Classes and Turtles be Turtling");
    String tower = convertToWhale("Tower of Terror");
    System.out.println(turtles);
    System.out.println(tower);
}

private static String convertToWhale(String phrase) {
    StringBuilder builder = new StringBuilder(phrase.length());
    char[] vowels = {'a', 'e', 'i', 'o', 'u'};
    for (char c : phrase.toCharArray()) {
        for (char vowel : vowels) {
            if (c == vowel) {
                builder.append(vowel).append(vowel);
            }
        }
    }
    return builder.toString().toUpperCase();
}

public static void main() {
    String turtles = convertToWhale("Normal Classes and Turtles be Turtling");
    String tower = convertToWhale("Tower of Terror");
    System.out.println(turtles);
    System.out.println(tower);
}

private static String convertToWhale(String phrase) {
    StringBuilder builder = new StringBuilder(phrase.length());
    char[] vowels = {'a', 'e', 'i', 'o', 'u'};
    for (char c : phrase.toCharArray()) {
        for (char vowel : vowels) {
            if (c == vowel) {
                builder.append(vowel).append(vowel);
            }
        }
    }
    return builder.toString().toUpperCase();
}