计算两个日期之间天数

private static int daysBetween(String smdate,String bdate) throws ParseException{
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
long to = df.parse(smdate).getTime();
long from = df.parse(bdate).getTime();
return (int) Math.abs((from - to) / (1000 * 60 * 60 * 24));
}