Процедура обработки события нажатия на кнопку

package frame;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;
class ListTest extends Frame implements ActionListener,WindowListener{
ListTest(String s) {super(s);
setLayout(null);
setFont(new Font("Serif", Font.BOLD, 15));
 
Label l1 = new Label("Длина:",Label.CENTER);
l1.setBounds(5,30,110,30); add(l1);
 
final TextField tf1 = new TextField(30);
tf1.setBounds(120,35,50,20); add(tf1);
 
Label l2 = new Label("Ширина:",Label.CENTER);
l2.setBounds(5,60,110,30); add(l2);
 
final TextField tf2 = new TextField(30);
tf2.setBounds(120,65,50,20); add(tf2);
 
Label l3 = new Label("Кол-во эт.:",Label.CENTER);
l3.setBounds(5,90,110,30); add(l3);
 
final TextField tf3 = new TextField(30);
tf3.setBounds(120,95,50,20); add(tf3);
 
Label l4 = new Label("руб.",Label.CENTER);
l4.setBounds(200,250,80,30); add(l4);
 
final Checkbox ch1 = new Checkbox("Мансарда");
ch1.setBounds(194,30,130,30); add(ch1);
 
Label l6 = new Label("Стены:",Label.CENTER);
l6.setBounds(170,60,100,30); add(l6); 
 
final List l = new List(2,true);
l.add("Кирпич"); l.add("Бетон");
l.setBounds(270,70,100,50); add(l);
 
Label l7 = new Label("Крыша:");
l7.setBounds(190,130,70,30); add(l7);
 
final Choice ch=new Choice();
ch.add("Черепица"); ch.add("Брус"); ch.add("Шифер");
ch.setBounds(270,130,100,30); add(ch);
 
Button bl=new Button("Рассчитать");
bl.setBounds(30,250,100,30); add(bl);
 
bl.addActionListener(this);
 
final TextField tf4 = new TextField(30);
tf4.setBounds(150,255,50,20); add(tf4);
 
class ActionListener{ 
private void Button1ActionPerformed(java.awt.event.ActionEvent evt) {
double h=2.2,s,b,e,kr=0,sten=0;int et;    
   e=Double.parseDouble(tf1.getText());
   b=Double.parseDouble(tf2.getText());
  et=Integer.parseInt(tf3.getText());
    if (l.getSelectedIndex()==0) sten=950;
  else if (l.getSelectedIndex()==1) sten=1300;
  if (ch.getSelectedIndex()==0) kr=950;
  else if (ch.getSelectedIndex()==1) kr=1300;
  else if (ch.getSelectedIndex()==2) kr=1500;
  if (ch1.isCursorSet()==true) kr*=1.5;
  s=2*h*(e+b)*sten*et+e*h*kr;
  tf4.setText(""+s/1000);
          }
 
    }
setSize(400, 300);setVisible(true);}
public static void main (String[] args){
    
    
ListTest f = new ListTest("Расчет стоимости дачного домика");
f.addWindowListener(new WindowAdapter(){
            @Override
    public void windowClosing(WindowEvent ev){System.exit(0); }});        
 
}
 
 
    @Override
    public void actionPerformed(ActionEvent e) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
 
    @Override
    public void windowOpened(WindowEvent e) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
 
    @Override
    public void windowClosing(WindowEvent e) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
 
    @Override
    public void windowClosed(WindowEvent e) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
 
    @Override
    public void windowIconified(WindowEvent e) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
 
    @Override
    public void windowDeiconified(WindowEvent e) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
 
    @Override
    public void windowActivated(WindowEvent e) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
 
    @Override
    public void windowDeactivated(WindowEvent e) {
        throw new UnsupportedOperationException("Not supported yet.");
    }
}