请教一下这程序有哪些地方不足

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;public class Menoy extends JFrame{
 JTextField text1;
 JButton but1,but2;
 JRadioButton Home,Industry;
  ButtonGroup radioGroup;
  JLabel lbl1;
  public  int a; 
  public Menoy(){
     super("电费收费系统");
     Container c=getContentPane();
     setSize(350,300);
     c.setBackground(Color.blue);
     lbl1=new JLabel("请选择用电类型");
     lbl1.setBounds(30,20,350,20);
     lbl1.setFont(new Font("TimesRoman",Font.BOLD,16));
     c.add(lbl1);
     text1=new JTextField(50);
     text1.setBounds(50,50,250,30);
     c.add(text1);   
     c.setLayout(null);      
     Home=new JRadioButton("家用电",false);
     Home.setBounds(55,90,100,30);
     Home.setFont(new Font("TimesRoman",Font.BOLD,14));
     c.add(Home);
     Home.addItemListener(new handler1());
     Industry=new JRadioButton("工业用电",false);
     Industry.setBounds(200,90,100,30);
     Industry.setFont(new Font("TimesRoman",Font.BOLD,14));
     c.add(Industry);      
     Industry.addItemListener(new handler2());
     radioGroup=new ButtonGroup();
     radioGroup.add(Home);
     radioGroup.add(Industry);
     but1=new JButton("计算");
     but1.setBounds(60,150,100,40);
     but1.setFont(new Font("TimesRoman",Font.BOLD,16));
     c.add(but1);
     but1.addActionListener(new jishu());
     but2=new JButton("清除");
     but2.setBounds(180,150,100,40);
     but2.setFont(new Font("TimesRoman",Font.BOLD,16));
     c.add(but2);
     but2.addActionListener(new Clear());
    show();
  } 
  public static void main(String ar[]){
    Menoy app=new Menoy();
    app.addWindowListener(new WindowAdapter(){
        public void windowClosing(WindowEvent e){
           System.exit(0);}});
  }
  
   private class handler1 implements ItemListener{
       public void itemStateChanged(ItemEvent e){
           a=1;
        }
   }
  
   private class handler2 implements ItemListener{
       public void itemStateChanged(ItemEvent e){
           a=2;
        }
   }
 private class jishu implements ActionListener{
       public void actionPerformed(ActionEvent e){        
        float value=(new Float(text1.getText())).floatValue();
           if(a==1)
           {  lbl1.setText("家用电");
             if(value<110)
               {  lbl1.setText("家用电在110度内:价格3元一度电:");
                   text1.setText(String.valueOf(value*3));}
               else if(value<330)
                {  lbl1.setText("家用电在110到330度之间:价格3.3元一度电:");
                   text1.setText(String.valueOf(value*3.3));}        
             else
                { lbl1.setText("家用电超过330度:价格3.5元一度电:");
                  text1.setText(String.valueOf(value*3.5));}
            }
         else if(a==2){
             lbl1.setText("工业用电:价格3元一度电");
             text1.setText(String.valueOf(value*3));  
           }
            else{lbl1.setText("请选择用电的类型:");}
         }
   }
  private class Clear implements ActionListener{
   public void actionPerformed(ActionEvent e){
         text1.setText("");        
         }
    }
}