java图形界面中的一个问题

编写一个用户注册界面，但是当输入用户和密码，在设定的复选框中确没有用户和密码得输入，请高手帮我看看哪里有问题
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Register extends JFrame{
String information;
JLabel nameLabel,passwordLabel,confirmpasswordLabel,sexLabel,birthdayLabel,yearLabel,monthLabel;
JTextField nameField;
JPasswordField passwordField;
JPasswordField confirmpasswordField;
JRadioButton radio1,radio2;
ButtonGroup group;
String birthdayyear[]={"1987","1988","1989","1990"};
String birthdaymonth[]={"1","2","3","4","5","6","7","8","9","10","11","12"};
JComboBox birthdayBoxYear,birthdayBoxMonth;
String name="",password="",confirmpassword="",sex="",birthdayYear="",birthdayMonth="";
JButton confirmBtn,cancelBtn;
public Register(){
super("用户注册");
Container container=getContentPane();
container.setLayout(new FlowLayout());
nameLabel=new JLabel("用户名");
nameField=new JTextField(10);
nameField.addActionListener(new NewActionListener());
container.add(nameLabel);
container.add(nameField);
passwordLabel=new JLabel("密码");
passwordField=new JPasswordField(10);
    passwordField.addActionListener(new NewActionListener());
    container.add(passwordLabel);
container.add(passwordField);
confirmpasswordLabel=new JLabel("确认密码");
    confirmpasswordField=new JPasswordField(10);
    confirmpasswordField.addActionListener(new NewActionListener());
    container.add(confirmpasswordLabel);
container.add(confirmpasswordField);
sexLabel=new JLabel("性别");
radio1=new JRadioButton("男");
    radio2=new JRadioButton("女");
    radio1.addItemListener(new RadioListener());
    radio2.addItemListener(new RadioListener());
    group=new ButtonGroup();
    group.add(radio1);
    group.add(radio2);
    container.add(sexLabel);
    container.add(radio1);
    container.add(radio2);
    birthdayLabel=new JLabel("生日");
    yearLabel = new JLabel("年");
    birthdayBoxYear  = new JComboBox(birthdayyear);
    birthdayBoxYear.addItemListener(new ComboListener1());
    monthLabel =  new JLabel ("月");
    birthdayBoxMonth  = new JComboBox(birthdaymonth);
    birthdayBoxMonth.addItemListener(new ComboListener2());
    
    container.add(birthdayLabel);
    container.add(yearLabel);
    container.add(birthdayBoxYear);
    container.add(monthLabel);
    container.add(birthdayBoxMonth);


    confirmBtn=new JButton("确认");
    cancelBtn=new JButton("取消 ");
    confirmBtn.addActionListener(new NewActionListener());
    cancelBtn.addActionListener(new NewActionListener());
    container.add(confirmBtn);
    container.add(cancelBtn);
    setSize(480,200);
    setVisible(true);
}
   class RadioListener implements ItemListener{
    public void itemStateChanged(ItemEvent e){
    Object item=e.getItemSelectable();
        if(item==radio1) sex=radio1.getLabel();
        else if(item==radio2) sex=radio2.getLabel();
    }
   }
   
   class ComboListener1 implements ItemListener{
    public void itemStateChanged(ItemEvent e){
    birthdayYear=(String)e.getItem();
    }
   }
   class ComboListener2 implements ItemListener{
    public void itemStateChanged(ItemEvent e){
    birthdayMonth = (String)e.getItem();
    }
   }
    class NewActionListener implements ActionListener{
     public void actionPerformed(ActionEvent e){
           if(e.getSource()==nameField){
            name+=nameField.getText();
           }
            else if(e.getSource()==passwordField){
            password+=passwordField.getText(); 
           }
            else if(e.getSource()==confirmBtn){
     information="用户名"+name+"\n密码"+password+"\n性别"+sex+"\n生日"+birthdayYear+" "+birthdayMonth;
                    JOptionPane.showMessageDialog(null,information);     
         }
           else if(e.getSource()==cancelBtn){
            System.exit(0);
           }
        }
 }
    public static void main(String args[]){
     Register re=new Register();
     re.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}