java获取字符串格式日期向前或向后n天的日期

private void setTilteMessage(){ 

        BaseDao dao = new BaseDao(); 

        String titleData = dao.getLatestData(); 

        dao.closeDB(); 

        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); 

        try { 

            Date date = sdf.parse(titleData); 

            Calendar   calendar   =   new   GregorianCalendar();  

            calendar.setTime(date);  

            calendar.add(calendar.DATE,1);//把日期往后增加一天.整数往后推,负数往前移动  

            date=calendar.getTime();   //这个时间就是日期往后推一天的结果  

            String putDate = sdf.format(date); //增加一天后的日期 

        } catch (ParseException e) { 

            e.printStackTrace(); 

        } 

    }