当用户输入完成后单击“立即注册”按，判断“密码”和“确认密码”文本框内容是否一致，如果一致在立即注册按钮上方显示用户输入的邮件地址，否则显示“密码不正确”。

/*   利用Java Swing技术设计一个Email邮箱地址注册的图形用户界面应用程序  */  
import java.awt.*;  
import java.awt.event.*;  
import javax.swing.*;

public class Email extends JFrame implements ActionListener {  
private static final long serialVersionUID = 2L;  //声明邮件地址、密码、确认密码、手机号码提示文字对应的标签组件  
JLabel labEmail, labPassword, labConfirmPass, labTel;  //声明输入邮件地址、手机号码的文本框组件  
JTextField txtEmail, txtTel;  //声明输入密码、确认密码的密码框组件  
JPasswordField txtPassword, txtConfirmPass;  //声明立即注册的按钮组件  
JButton btnRegister;  //声明一个TextArea组件放到立即注册按钮的下方  
JLabel labInfo;  
JPanel jpw, jpTop, jpBottom, jpInfo;

public Email () {  //创建一个显示面板  
jpw = new JPanel();  
jpw.setLayout(new BorderLayout());

jpTop = new JPanel();  
jpTop.setLayout(new GridLayout(4, 2));

jpBottom = new JPanel();  
jpBottom.setLayout(new FlowLayout());

jpInfo = new JPanel();  
jpInfo.setLayout(new FlowLayout());  //初始化每一个图形化界面中显示的组件  
labEmail = new JLabel("邮件地址");  
labPassword = new JLabel("密       码");  
labConfirmPass = new JLabel("确认密码");  
labTel = new JLabel("手机号码");

txtEmail = new JTextField(20);  
txtTel = new JTextField(20);

txtPassword = new JPasswordField(20);  
txtConfirmPass = new JPasswordField(20);

btnRegister = new JButton("立即注册");  
btnRegister.addActionListener(this);

labInfo = new JLabel();  //把需要显示的组件放到显示面板中  
jpTop.add(labEmail);  
jpTop.add(txtEmail);  
jpTop.add(labPassword);  
jpTop.add(txtPassword);  
jpTop.add(labConfirmPass);  
jpTop.add(txtConfirmPass);  
jpTop.add(labTel);  
jpTop.add(txtTel);

jpBottom.add(btnRegister);

jpInfo.add(labInfo);

jpw.add(jpTop, BorderLayout.NORTH);  
jpw.add(jpBottom, BorderLayout.SOUTH);  
jpw.add(jpInfo, BorderLayout.CENTER);  //把显示面板添加到窗口中  
this.add(jpw);  //设置显示窗口的标题  
this.setTitle("Email注册");  //设置显示窗口的最初大小  
this.setSize(320, 200);  //设置显示窗口是否显示  
this.setVisible(true);  
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  
}

public void actionPerformed(ActionEvent e) {  
String txt = "邮箱为：" + txtEmail.getText();  
@SuppressWarnings("deprecation")  
String pwd = txtPassword.getText();  
@SuppressWarnings("deprecation")  
String confirmPwd = txtConfirmPass.getText();  
if(pwd.equalsIgnoreCase(confirmPwd)) {  
labInfo.setText(txt);  
} else {  
labInfo.setText("密码不正确");  
}  
}

public static void main(String[] args) {  
new Email();  
}

}