Développement Android : Convertir des millisecondes (au format "string") en date

private String convertMillisecondsToDate(String value) {
    String finalDateString = "";
    try {
        long milliSeconds = Long.parseLong(value);
        DateFormat formatter = new SimpleDateFormat("dd/MM/yyyy HH:mm:ss.SSS");
        Calendar calendar = Calendar.getInstance();
        calendar.setTimeInMillis(milliSeconds);
        finalDateString = formatter.format(calendar.getTime());
        //Log.d(TAG, "date parsed =" + finalDateString);    }
    catch(Exception pe) {
        Log.d(TAG, "date parsing exception:" + pe.toString());
    }
    return finalDateString;
}