class Strings {

    public static String join(List<String> src, String delimiter) {
        if (src != null) {
            StringBuilder builder = new StringBuilder();
            if (!src.isEmpty()) {
                builder.append(src.get(0));
            }
            for (int i = 1; i < src.size(); i++) {
                builder.append(delimiter).append(src.get(i));
            }
            return builder.toString();
        }
        return null;
    }

    private  Strings();

}