java通过选择年月生成天下拉框

private void  changeDayComboBox(String dyear,String dmouth){
SimpleDateFormat simpleDate = new SimpleDateFormat("yyyy/MM");
Calendar rightNow = Calendar.getInstance();
try{
rightNow.setTime(simpleDate.parse(dyear+"/"+dmouth));
}catch(ParseException e){
e.printStackTrace();
}
int days = rightNow.getActualMaximum(Calendar.DAY_OF_MONTH);//根据年月 获取月份天数
DefaultComboBoxModel list = new DefaultComboBoxModel();
for(int i = 0; i < days; i++){
list.addElement(i+1);
}
m_DayComboBox.setModel(list);
}

changeDayComboBox("2015","7");