import java.awt.*;
import java.applet.*;
import java.awt.event.*;
import javax.swing.*;
public class bbb extends JApplet implements WindowListener,ActionListener,ItemListener 
{
  JOptionPane p1=new JOptionPane();
  JLabel l1=new JLabel("name");
  JLabel l2=new JLabel("nosmoking seat distinct");
  JLabel l3=new JLabel("smoking seat distinct");
  JCheckBox c1=new JCheckBox();
  JCheckBox c2=new JCheckBox();
  JTextField t=new JTextField(10);
  JButton b=new JButton("确定");
  
  
  public bbb()
  {
   Container container = getContentPane();
   container.setLayout(new FlowLayout());  
   
   container.add(l1);
   container.add(t );
   container.add(l2);
   container.add(c1);
   c1.addItemListener(this);
     container.add(l3);    
   container.add(c2);
   c2.addItemListener(this);
   container.add(b);
     b.addActionListener(this); 
   }  
   public void windowClosing(WindowEvent e){System.exit(0);}     
     public void windowOpened(WindowEvent e){}
     public void windowIconified(WindowEvent e){}
     public void windowDeiconified(WindowEvent e){}
     public void windowClosed(WindowEvent e){}
     public void windowActivated(WindowEvent e){}
     public void windowDeactivated(WindowEvent e){}

     public void itemStateChanged(ItemEvent e)
     {
      
       if(e.getSource()==c1&&e.getSource()==c2)
       {
              
             p1.showMessageDialog(null,"error");
            
       }
       
     }  
       
   public void actionPerformed(ActionEvent e)
    { 
      
      if(e.getSource()==b)
       {
         if(t.getText()=="")
          {
          
           p1.showMessageDialog(null,"name is null."); 
        
         }
      }
    }
}