How to insert a syllable before a single vowel

Question

I try to insert a syllable before each vowel with the following restrictions:

- Before each following vowel (a, e, i, o, u), insert the stray syllable "av".

- Unless the vowel is preceded by another vowel

Actually I've done this

public static String translate(String text) {
    char [] charArray = text.toCharArray();
    StringBuilder sb = new StringBuilder();

    for(char c : charArray) {
        if (charArray.length < 255){
            if (isVowel(c)) {
                sb.append(String.format("av%s" , c));
            }
            else {
                sb.append(c);
            }
        }
    }
    return sb.toString();
}

static boolean isVowel(char c) {
    return (c == 'a') || (c == 'e') ||
            (c == 'i') || (c == 'o') ||
            (c == 'u');
}

With words without double vowels it works perfectly:

Cat becomes

Cavat

But with double vowel it doesn't work

Meet becomes

Maveavet // Should return Meet

How to check if 2 successive letters are vowels in order not to add the syllable if it's the case ?

Thanks in advance

Answer 1

Here is a version that uses an ordinary for loop:

public static String translate(String text) {
    char [] charArray = text.toCharArray();
    StringBuilder sb = new StringBuilder();

    Set<Character> vowels = new HashSet<>(Arrays.asList('a','e','i','o','u'));

    char cFirst = charArray[0];
    if (vowels.contains(cFirst) && !(vowels.contains(charArray[1]))) {
        sb.append(String.format("av%s" , cFirst));
    }
    else sb.append(cFirst);

    for (int i = 1; i < charArray.length-1; i++){
        char c = charArray[i];
        char cNext = charArray[i+1];
        char cPrev = charArray[i-1];

        if (vowels.contains(c) && !(vowels.contains(cNext) || vowels.contains(cPrev))) {
            sb.append(String.format("av%s" , c));
        }
        else sb.append(c);
    }

    char cLast = charArray[charArray.length-1];
    if (vowels.contains(cLast) && !(vowels.contains(charArray[charArray.length-2]))) {
        sb.append(String.format("av%s" , cLast));
    }
    else sb.append(cLast);

    return sb.toString();
}

Works for all the cases I could think of, but probably not the optimal way of doing this.