JAVA获取指定月份的天数

        Calendar ymCalendar=Calendar.getInstance();
  Date ymDate=new Date();
  ymDate.setYear(Integer.parseInt(CommonUtils.getYear(kokanDayForm.getKokanYm())));
  ymDate.setMonth(Integer.parseInt(CommonUtils.getMonth(kokanDayForm.getKokanYm()))-1);
  ymDate.setDate(1);
  ymCalendar.setTime(ymDate);
        int  dayOfMonthCount=ymCalendar.getActualMaximum(Calendar.DAY_OF_MONTH)  ;
       
        String[] displayValues=new String[dayOfMonthCount];
        for(int i=0;i<dayOfMonthCount;i++){
            displayValues[i]="1";
        }