public static Double fromDate(Date date) {
    if (date==null) {
        return(null);
    }
    Long d = date.getTime()/1000;
    return(d.doubleValue());
}

public static Date toDate(Double millisSinceEpoch) {
    if (millisSinceEpoch==null) {
        return(null);
    }

    Long d = Math.round(millisSinceEpoch*1000);
    return(new Date(d));
}
public static String toDateString(Double millisSinceEpoch){
    Date date = toDate(millisSinceEpoch);
    String pattern = "yyyy-MM-dd";
    SimpleDateFormat simpleDateFormat = new SimpleDateFormat(pattern);
    return simpleDateFormat.format(date);
}