用java设计一个简单的界面可以参考如下实例：

import javax.swing.JPanel//面板

import javax.swing.JButton//按钮

import javax.swing.JLabel//标签

import javax.swing.JTextField//文本框

import java.awt.Font//字体

import java.awt.Color//颜色

import javax.swing.JPasswordField//密码框

import java.awt.event.ActionListener//事件监听

import java.awt.event.ActionEvent//事件处理

import javax.swing.JOptionPane//消息窗口public class UserLogIn extends JFrame{

 public JPanel pnluser

 public JLabel lbluserLogIn

 public JLabel lbluserName

 public JLabel lbluserPWD

 public JTextField txtName

 public JPasswordField pwdPwd

 public JButton btnSub

 public JButton btnReset

 public UserLogIn(){

  pnluser = new JPanel()

  lbluserLogIn = new JLabel()

  lbluserName = new JLabel()

  lbluserPWD = new JLabel()

  txtName = new JTextField()

  pwdPwd = new JPasswordField()

  btnSub = new JButton()

  btnReset = new JButton()

  userInit()

 }

 public void userInit(){

  this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)//设置关闭框架的同时结束程序

  this.setSize(300,200)//设置框架大小为长300,宽200

  this.setResizable(false)//设置框架不可以改变大小

  this.setTitle("用户登录")//设置框架标题

  this.pnluser.setLayout(null)//设置面板布局管理

  this.pnluser.setBackground(Color.cyan)//设置面板背景颜色

  this.lbluserLogIn.setText("用户登录")//设置标签标题

  this.lbluserLogIn.setFont(new Font("宋体",Font.BOLD | Font.ITALIC,14))//设置标签字体

  this.lbluserLogIn.setForeground(Color.RED)//设置标签字体颜色

  this.lbluserName.setText("用户名:")

  this.lbluserPWD.setText("密    码:")

  this.btnSub.setText("登录")

  this.btnReset.setText("重置")

  this.lbluserLogIn.setBounds(120,15,60,20)//设置标签x坐标120,y坐标15,长60,宽20

  this.lbluserName.setBounds(50,55,60,20)

  this.lbluserPWD.setBounds(50,85,60,25)

  this.txtName.setBounds(110,55,120,20)

  this.pwdPwd.setBounds(110,85,120,20)

  this.btnSub.setBounds(85,120,60,20)

  this.btnSub.addActionListener(new ActionListener()//匿名类实现ActionListener接口

   {

    public void actionPerformed(ActionEvent e){

     btnsub_ActionEvent(e)

    }    

   }

  ) 

  this.btnReset.setBounds(155,120,60,20)

  this.btnReset.addActionListener(new ActionListener()//匿名类实现ActionListener接口

   {

    public void actionPerformed(ActionEvent e){

     btnreset_ActionEvent(e)

    }    

   }

  )   

  this.pnluser.add(lbluserLogIn)//加载标签到面板

  this.pnluser.add(lbluserName)

  this.pnluser.add(lbluserPWD)

  this.pnluser.add(txtName)

  this.pnluser.add(pwdPwd)

  this.pnluser.add(btnSub)

  this.pnluser.add(btnReset)

  this.add(pnluser)//加载面板到框架

  this.setVisible(true)//设置框架可显  

 }

 public void btnsub_ActionEvent(ActionEvent e){

  String name = txtName.getText()

  String pwd = String.valueOf(pwdPwd.getPassword())

  if(name.equals("")){

   JOptionPane.showMessageDialog(null,"账号不能为空","错误",JOptionPane.ERROR_MESSAGE)

   return

  }else if (pwd.equals("")){

   JOptionPane.showMessageDialog(null,"密码不能为空","错误",JOptionPane.ERROR_MESSAGE)

   return

  }else if(true){

   this.dispose()

  }else{

   JOptionPane.showMessageDialog(null,"账号或密码错误","错误",JOptionPane.ERROR_MESSAGE)

   return

  }

 }

 public void btnreset_ActionEvent(ActionEvent e){

  txtName.setText("")

  pwdPwd.setText("")

 }

 public static void main(String[] args){

  new UserLogIn()

 }

}

import javax.swing.*

public class Tabbed {

    public static void main(String[] args) {

        EventQueue.invokeLater(new Runnable(){

            @Override public void run(){

                final JFrame frame = new JFrame("my window")

                final JMenuBar menubar = new JMenuBar()

                final JMenu fileMenu = new JMenu("File")

                menubar.add(fileMenu)

                frame.setJMenuBar(menubar)

                final JTabbedPane tabbed = new JTabbedPane(JTabbedPane.LEFT)

                tabbed.addTab("Main", new JPanel())

                tabbed.addTab("Setting", new JPanel())

                tabbed.addTab("Email", new JPanel())

                tabbed.addTab("Security", new JPanel())

                frame.add(tabbed)

                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)

                frame.setPreferredSize(new Dimension(800,600))

                frame.pack()

                frame.setVisible(true)

            }

        })

    }

}

自己根据需要修改