package study;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

//import javax.swing.event.*;

public class CheckLogin extends JFrame implements ActionListener,ItemListener {
    JLabel user = new JLabel("用户：");
    JLabel pass = new JLabel("密码：");
    public String[] username = {"王平", "李四", "张三"};
    JComboBox users = new JComboBox(username);
    JButton login = new JButton("登录");
    JPasswordField password = new JPasswordField(10);
    //public char pw[] = {'d','d'};
    public CheckLogin(){
        JPanel pane = new JPanel();
        //Container cont = getContentPane();
        pane.add(user);
        pane.add(users);
        pane.add(pass);
        pane.add(password);
        pane.add(login);
        pane.setLayout(new FlowLayout());
        add(pane);
        password.addActionListener(this);
        users.addItemListener(this);
        login.addActionListener(this);
    }
    public static void main(String args[]){
        //Checklogin frame=new BorderLayoutTest();
        CheckLogin cl = new CheckLogin();
        cl.setTitle("用户登录页面");
        cl.setVisible(true);
        cl.setSize(500,300);
        cl.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    public String setpwb(){
        int flag = 0;
        String pwb[] = {"123456", "112233", "123123"};
        String pw;
        while(true){
            if (users.getSelectedItem() == username[flag]){
                pw = pwb[flag];
                break;
            }
            flag++;
        }
        return pw;
    }
    public void itemStateChanged(ItemEvent ex) {
        // TODO Auto-generated method stub
    }
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub
        String passw = new String(password.getPassword());
        if (e.getSource() == login){
            if (passw.equals(setpwb())){
                String dialogTitle = "提示";
                String dialogMessage = "登录成功！";
                int dialogType = JOptionPane.INFORMATION_MESSAGE;
                JOptionPane.showMessageDialog((Component)null, dialogMessage, dialogTitle, dialogType);
                return;
            }
        String dialogTitle = "提示";
        String dialogMessage = "登录失败！";
        int dialogType = JOptionPane.ERROR_MESSAGE;
        JOptionPane.showMessageDialog((Component)null, dialogMessage, dialogTitle, dialogType);
        }
    }
}




把这个程序该成  



用户名          名字



密码              输入密码的文本框     



       登陆   

我是个初学者。

好像 有点错误。无法运行。

没有  界面。如果你有软件的话 可以试试。

可不可以把 文本框和密码框的大小 叫他们固定下来。