How to shuffle characters in a string without using Collections.shuffle(…)?

Question

How do I shuffle the characters in a string (e.g. hello could be ehlol or lleoh or ...). I don\'t want to use the Collections.shuffle(...) method, is there anyt

Answer 1

Here's code that requires neither recursion, nor converting to a Collection.

public static String shuffle(String string) {
    StringBuilder sb = new StringBuilder(string.length());
    double rnd;
    for (char c: string.toCharArray()) {
        rnd = Math.random();
        if (rnd < 0.34)
            sb.append(c);
        else if (rnd < 0.67)
            sb.insert(sb.length() / 2, c);
        else
            sb.insert(0, c);
    }       
    return sb.toString();
}