ComboBox hell

Question

I am trying to write code that will check whether the date entered by the user is valid. The following code works but only with the first month chosen e.g. if the user selects 31 Feburary the correct Dialog box will be displayed. I would like it so that if the user selects another month and an invalid date e.g. 30 April the correct dioalg box will appear to warn the user. The problem is that the month doesn't change it always stays on the month, in the above example Feburary. I have tried to create a new String but it doesn't seem to change any thing. Here are the relevent snipets of the code
private Integer selectedDay;
String selectedMonth;
//Report start day combo box settings
startDay = new JComboBox(days);
startDay.setPreferredSize(new Dimension(55, 30));
startDay.setFont(comboText);
panel.add(startDay);
layout.putConstraint(SpringLayout.WEST, startDay,200, SpringLayout.WEST, panel);
layout.putConstraint(SpringLayout.NORTH, startDay, 95, SpringLayout.NORTH, panel);
startDay.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
startDayActionEvent(evt);
//Report start month combo box setttings
startMonth = new JComboBox(months);
startMonth.setPreferredSize(new Dimension(100, 30));
startMonth.setFont(comboText);
panel.add(startMonth);
layout.putConstraint(SpringLayout.WEST,startMonth,255, SpringLayout.WEST, panel);
layout.putConstraint(SpringLayout.NORTH, startMonth,95, SpringLayout.NORTH, panel);
startMonth.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
startMonthActionEvent(evt);
private String startDayActionEvent(ActionEvent evt){
selectedDay = new Integer(dayn);
JComboBox cb = (JComboBox)evt.getSource();
selectedDay = (Integer)cb.getSelectedItem();
if(selectedMonth != null){
checkDays.check(selectedDay, selectedMonth, cb);
else if (selectedMonth == null);
return null;
private void startMonthActionEvent(ActionEvent evt){
JComboBox cb = (JComboBox)evt.getSource();
selectedMonth = (String) cb.getSelectedItem();
selectedMonth = checkDays.check(selectedDay, selectedMonth, cb);
selectedMonth = new String(selectedMonth);
//check mehtod in class Days
public String check(Integer days, String month, JComboBox cb){int theDay = days.intValue();
         if((theDay > 28) && (month.equals("Feburary"))){
               JOptionPane.showMessageDialog(null, "Invalid date.\nThere are only 28 days in Feburary");
               cb.setSelectedIndex(27);
               return null;
     else if((theDay > 30 ) && (month.equals("April"))){
     JOptionPane.showMessageDialog(null, "Invalid date.\nThere are only 30 days in April");
     cb.setSelectedIndex(29);
     return null;
     else if((theDay > 30 ) && (month.equals("June"))){
     JOptionPane.showMessageDialog(null, "Invalid date.\nThere are only 30 days in June");
     cb.setSelectedIndex(29);
     return null;
     else if((theDay > 30 ) && (month.equals("September"))){
     JOptionPane.showMessageDialog(null, "Invalid date.\nThere are only 30 days in September");
     cb.setSelectedIndex(29);
     return null;
     else if((theDay > 30 ) && (month.equals("November"))){
     JOptionPane.showMessageDialog(null, "Invalid date.\nThere are only 30 days in November");
     cb.setSelectedIndex(29);
     return null;
     else;
     return null;
     }

Answer 1

I took a break, came back and realised my mistake. Thanks anyway.