计算2个日期之间的天数差距

public static long dValue(String start,String end)  {    SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd");    long t=0;    try{        Date dstart = sf.parse(start);        Date dend = sf.parse(end);        Calendar c1 = Calendar.getInstance();        Calendar c2 = Calendar.getInstance();        int month = c1.get(Calendar.MONTH);        c1.setTime(dstart);        c2.setTime(dend);        int syear = c1.get(Calendar.YEAR);        int smonth = c1.get(Calendar.MONTH)+1;        int sday = c1.get(Calendar.DATE);        int eyear = c2.get(Calendar.YEAR);        int emonth = c2.get(Calendar.MONTH)+1;        int eday = c2.get(Calendar.DATE);        c1.set(syear,smonth,sday);        c2.set(eyear,emonth,eday);        t = (c2.getTimeInMillis()-c1.getTimeInMillis())/(1000*60*60*24);    }catch (ParseException e){    }    return t+1;}