Java Calendar 計算時間差

public static void main(String[] args) {
        Calendar c=Calendar.getInstance();
        int y=2016;//年
        int M=1;//月
        int d=1;//日
        int H=0;//時
        int m=0;//分
        int s=0;//秒
        c.set(Calendar.YEAR, y);
        c.set(Calendar.MONTH, M-1);
        c.set(Calendar.DATE, d);
        c.set(Calendar.HOUR_OF_DAY, H);
        c.set(Calendar.MINUTE, m);
        c.set(Calendar.SECOND, s);
        Calendar now=Calendar.getInstance();
        long aTime=now.getTimeInMillis();
        long bTime=c.getTimeInMillis();
        long cTime=aTime-bTime;
        long sTime=cTime/1000;//時間差，單位：秒
        long mTime=sTime/60;
        long hTime=mTime/60;
        long dTime=hTime/24;
        SimpleDateFormat f=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        System.out.println("當前時間："+f.format(now.getTime()));
        System.out.println("設定時間："+f.format(c.getTime()));
        System.out.println("時間差："+dTime+"天"+hTime%24+"時"+mTime%60+"分"+sTime%60+"秒");
    }