Java gets the current date and date before and after days __java

if (StartTime = null | | starttime.length () = 0 | | endtime = NULL | | endtime.length () = 0) {
    //Get current date
    Simpleda Teformat df = new SimpleDateFormat ("YyyyMMdd"); Format Date
    nowdate = new Date ();
    String nowtime = Df.format (nowdate); 20170410
    //Get the date of the first 5 days of the
    calendar now = Calendar.getinstance ();
    Now.settime (nowdate);
    Now.set (Calendar.date, Now.get (calendar.date)-5);
    Date predate = Now.gettime ();
    String pretime = Df.format (predate); 20170405

    starttime = pretime;//20170405
    endtime = nowtime;//20170410
}