Customer price

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JRootPane;
import javax.swing.JTextField;

class   NewFrame extends JFrame implements ActionListener {
    JPanel panel = new JPanel();
      JPanel toppanel=new JPanel();
      JPanel middlepanel=new JPanel();
      JPanel bottompanel=new JPanel();
         private JButton PressResult;
          String sex[]={"Male","Female"};
          String subject[] = {"Standard", "Gold", "Premimum", "Diamond"};
          private double discount;
          private JTextField memnum, listprice;
          private JTextField result;
    NewFrame()
    {
      JLabel label0=new JLabel("Customer List price");
      listprice=new JTextField(5);
      listprice.setText("10000");
      JLabel label1=new JLabel("First name");
       JTextField first=new JTextField(5);
       JLabel label2=new JLabel("Middle name");
       JTextField middle=new JTextField(5);
       JLabel label3=new JLabel("Last name");
       JTextField last=new JTextField(5);
       JLabel label4=new JLabel("Gender");
       JComboBox<String> gender=new JComboBox<String>(sex);
       JLabel label5=new JLabel("Membership");
       final JComboBox<String> membership = new JComboBox<String>(subject);
       membership.addActionListener(this);
       membership.addActionListener(new ActionListener() {
           public void actionPerformed(ActionEvent e) {
               System.out.println("The membership is "+ membership.getSelectedItem());
               String choice=(String)membership.getSelectedItem();
               switch(choice) {
               case "Standard":
                   discount=1;
                   break;
               case "Gold":
                   discount=0.9;
                   break;
               case "Premimum":
                   discount=0.85;
                   break;
               case "Diamond":
                   discount=0.75;
                    break;
                    default:
                        break;
               } 
               panel.updateUI();
           }
       });
      
   //    JTextField membership=new JTextField(5);
       JLabel label6=new JLabel("membership number");
 memnum=new JTextField(5);
      
      panel.add(toppanel);
      panel.add(middlepanel);
      panel.add(bottompanel);
     
     
      panel.setLayout(new GridLayout(3,1 ));
        setUndecorated(true);
        getRootPane().setWindowDecorationStyle(JRootPane.PLAIN_DIALOG);
        toppanel.add(label0);
       toppanel.add(listprice);      
       toppanel.add(label1);
       toppanel.add(first);
       toppanel.add(label2);
       toppanel.add(middle);
       toppanel.add(label3);
       toppanel.add(last);
       toppanel.add(label4);
       toppanel.add(gender);
       toppanel.add(label5);
       toppanel.add(membership);
       toppanel.add(label6);
       toppanel.add(memnum);     
     
       
       result=new JTextField();
        PressResult=new JButton("Press to get purchase price");
        PressResult.addActionListener(this);
        bottompanel.add(PressResult);
        result=new JTextField(5);
        bottompanel.add(result);       
       
        add(panel);
        setSize(500,400);
        setVisible(true);
        setTitle("Customer price");       
       
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);   
  
    }
    public void actionPerformed(ActionEvent e) {
    //    System.out.println("testing99:" +e.getActionCommand());
       if (e.getActionCommand().equals("comboBoxChanged")) comboselect(e);
      if (e.getActionCommand().equals("Press to get purchase price")) gettotal(e);  
    }
    void  comboselect(ActionEvent e){
       
       JLabel label21=new JLabel("membership discount");       
        JTextField memcut=new JTextField(5);
        memcut.setText(Double.toString(discount));
    
        middlepanel.removeAll();
       repaint();      
        middlepanel.add(label21);
        middlepanel.add(memcut);
       
    }
    public void gettotal(ActionEvent e){
        double total=0;
        int num=0, listpricen;
        num=Integer.parseInt(memnum.getText());
        listpricen=Integer.parseInt(listprice.getText());
        total=discount*num*listpricen;  
            result.setText(Double.toString(total));
           result.updateUI();
       
    }
 }

 public class CustomerGUI {
  public static void main(String[] args) {   
   new NewFrame();  
    } 
 }