計算兩個日期之間天數

  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));
  }