日期遞增遞減--GregorianCalendar 使用

 @Test
    public void demo01(){
        //日期遞增遞減
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMdd");
        Date date = new Date();//遞增前的數
        System.out.println(dateFormat.format(date));
      //  System.out.println(date);
        GregorianCalendar calendar = new GregorianCalendar();
        calendar.setTime(date);
        calendar.add(Calendar.DATE,2);//正數往前加,負數減
        date=calendar.getTime();//遞增後的數
        System.out.println(dateFormat.format(date));   
        //System.out.println(date);
    }