java swing初体验

import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JRadioButton;
import javax.swing.JTextField;

public class RegPanel extends JFrame {
    public static final int WIDTH = 250;
    public static final int HEIGHT = 260;
    public RegPanel(){
        setTitle("新用户注册");
        JPanel panel = new JPanel(new FlowLayout(FlowLayout.CENTER));
        
        JPanel p1 = new JPanel();
        JLabel label1 = new JLabel("用  户  名");
        final JTextField userName = new JTextField(15);
        p1.add(label1);
        p1.add(userName);
        panel.add(p1);
        
        JPanel p2 = new JPanel();
        JLabel label2 = new JLabel("密        码");
        final JPasswordField password = new JPasswordField(15);
        p2.add(label2);
        p2.add(password);
        panel.add(p2);
        
        JPanel p3 = new JPanel();
        JLabel label3 = new JLabel("确认密码");
        final JPasswordField rePassword = new JPasswordField(15);
        p3.add(label3);
        p3.add(rePassword);
        panel.add(p3);
        
        JPanel p4 = new JPanel();
        JLabel sex = new JLabel("性别");
        final ButtonGroup group = new ButtonGroup();
        final JRadioButton male = new JRadioButton("男");
        male.setSelected(true);
        final JRadioButton female = new JRadioButton("女");
        group.add(male);
        group.add(female);
        p4.add(sex);
        p4.add(male);
        p4.add(female);
        panel.add(p4);
        
        JPanel p5 = new JPanel();
        JLabel label5 = new JLabel("感兴趣的课程");
        final JCheckBox c = new JCheckBox("C");
        final JCheckBox java = new JCheckBox("Java");
        final JCheckBox en = new JCheckBox("英语");
        p5.add(label5);
        p5.add(c);
        p5.add(java);
        p5.add(en);
        panel.add(p5);
        
        JPanel p6 = new JPanel(new FlowLayout(FlowLayout.CENTER));
        JButton reg = new JButton("注册");
        JButton clear = new JButton("清空");
        p6.add(reg);
        p6.add(clear);
        panel.add(p6);
        
        reg.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                String un = userName.getText();
                char[] pw = password.getPassword();
                char[] repw = rePassword.getPassword();
                String sex = male.isSelected()?male.getText():female.getText();
                StringBuffer hobby = new StringBuffer();
                hobby.append(c.isSelected()?c.getText()+"\t":"");
                hobby.append(java.isSelected()?java.getText()+"\t":"");
                hobby.append(en.isSelected()?en.getText()+"\t":"");
                System.out.println("用户名："+un);
                System.out.println("密码：" + new String(pw));
                System.out.println("重复密码：" + new String(repw));
                System.out.println("性别：" + sex);
                System.out.println("兴趣："+hobby);
            }
        });
        
        clear.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                userName.setText("");
                password.setText("");
                rePassword.setText("");
                male.setSelected(true);
                c.setSelected(false);
                java.setSelected(false);
                en.setSelected(false);
            }
        });
        this.add(panel);
        init();
    }
    
    public void init(){
        Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
        int x = (int) ((d.getWidth()-WIDTH)/2);
        int y = (int) ((d.getHeight()-HEIGHT)/2);
        setBounds(x, y, WIDTH, HEIGHT);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setVisible(true);
        setResizable(false);
    }
    public static void main(String[] args) {
        new RegPanel();
    }
}