Java Quartz calculates nearly 20 execution times

    /*** * @desc calculation expression nearly 20 times * @auth Josnow * @date May 31, 2017 pm 12:16:25 *@paramCron *@return     */     Public StaticList<string> seeexcutetime (String cron)throwsParseException, illegalargumentexception {if(Stringutils.isempty (cron)) {Throw NewIllegalArgumentException ("parameter cannot be empty"); } cronsequencegenerator cronsequencegenerator=NewCronsequencegenerator (cron); SimpleDateFormat SDF=NewSimpleDateFormat ("Yyyy-mm-dd HH:mm:ss"); List<String> list =NewArraylist<> (20); Date Nexttimepoint=NewDate ();  for(inti = 0; I < 20; i++) {            //calculate the start time of the next point in timeNexttimepoint =Cronsequencegenerator.next (Nexttimepoint);        List.add (Sdf.format (nexttimepoint)); }        returnlist; }     Public Static voidMain (string[] args)throwsException {List<String> list = Seeexcutetime ("0 0 * * *?"));  for(inti = 0; I < list.size (); i++) {System.out.println (List.get (i)); }    }

Java Quartz calculates nearly 20 execution times