java 怎么计算当日的前几天日期 解决方法

public static void main(String[] args)
    {
        Date date = new Date();
        System.out.println((new SimpleDateFormat("yyyy-MM-dd")).format(date));
       Calendar cal = Calendar.getInstance();
       cal.setTime(date);
       cal.add(Calendar.DATE, -1);
       System.out.println((new SimpleDateFormat("yyyy-MM-dd")).format(cal.getTime()));
    }