java - Writing dates in csv files, some output as ###### -

i writing application let threads write csv files random numbers , random dates. however, of dates output ######, when click them in excell, show correct date (e.g.11/4/2014 shows ###### in excell, when click on cell, in fx field show 11/4/2014).

here how write dates:

    random random = new random();     bufferedwriter bufferedwriter;     gregoriancalendar cal = new gregoriancalendar();     dateformat df = new simpledateformat("dd/mm/yyyy");       writeline(random, bufferedwriter, cal, df);  private void writeline(random random, bufferedwriter bufferedwriter, gregoriancalendar cal, dateformat df) throws ioexception {         string randomdatestring;         bufferedwriter.write(double.tostring(random.nextdouble() * 100));         bufferedwriter.write(",");         randomdatestring = createrandomdate(random, cal, df);         bufferedwriter.write(randomdatestring);         bufferedwriter.newline();     }   private string createrandomdate(random random, gregoriancalendar cal, dateformat df) {         int randomdayoftheyear;         date randomdate;         string randomdatestring;         randomdayoftheyear = random.nextint(365) + 1;         cal.set(calendar.year, 2014);         cal.set(calendar.day_of_year, randomdayoftheyear);         randomdate = cal.gettime();         randomdatestring = df.format(randomdate);         return randomdatestring;     } 

###### piece of text excel uses mark cells not wide enough display entire number within them. happens numbers. writing csv file correctly. have expand column in excel can display whole date.