JOptionPane.showMessageDialog(null,"请输入用户名!","提示消息",JOptionPane.WARNING_MESSAGE);
}else if(jpf.getText().isEmpty())
{
JOptionPane.showMessageDialog(null,"请输入密码!","提示消息",JOptionPane.WARNING_MESSAGE);
}else
{
JOptionPane.showMessageDialog(null,"用户名或者密码错误!\n请重新输入","提示消息",JOptionPane.ERROR_MESSAGE);
clear(); //清空输入框
}
}
//清空文本框和密码框
public void clear()
{
jtf.setText("");
jpf.setText("");
}
}
运行图1
用户名和密码如下:
2.完成学生界面StuUI,这个页面在MainUI界面设置了按钮连接(代码如下)
package com.pag_1;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.JButton;
import java.awt.color.*;
import javax.swing.JOptionPane;
import com.pag_1.MainUI;
public class StdUI extends JFrame implements ActionListener
{
//定义组件
JButton jb1=new JButton();
JButton jb2=new JButton();
JPanel jp1,jp2,jp3,jp4=null;
JLabel jlb1,jlb2,jlb3,jlb4,jlb5,jlb6=null;
public static void main(String[] args)
{
StdUI ui=new StdUI();
}
//****************************事件判断**********************
//构造函数
public StdUI() //不能申明为void!!!!!否则弹不出新界面
{
//创建组件