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");  

    }