How to use getText()

Các bạn cho mình hỏi về cách sử dụng getText()?
Mình có code như sau nhưng khi khởi chạy không thể lấy được giá trị nhập:
mong các bạn chỉ bảo!! ^^
package Test3;
import java.awt.*;
import java.awt.event.*;
public class Sample3 extends Frame
{
 private Label lb;
 String tx, ts;
 Button bt;
 Image im;
 int h,w;

 public static void main(String[] args)
 {
 Sample3 sm=new Sample3();
 }
 public Sample3()
 {
 super("サンプル");
 lb = new Label("BMI???");

 add(lb);
 lb.setForeground(Color.green);
 lb.setFont(new Font("Serif", Font.BOLD,30));

 addWindowListener(new SampleWindowListener());

 setSize(600,400);
 setVisible(true);

 Toolkit tk= getToolkit();
 im = tk.getImage("images.jpeg");
 setVisible(true);

 lb= new Label("身長？");
 add(lb);
 lb.setFont(new Font("Serif",Font.BOLD,15));
 TextField tx = new TextField(3);
 add(tx);

 lb= new Label("体重？");
 add(lb);
 lb.setFont(new Font("Serif",Font.BOLD,15));
 TextField ts = new TextField(3);
 add(ts);

 bt = new Button("SEND");
 add(bt);
 bt.addActionListener(new SampleActionListener());

 setLayout(new GridLayout(10,1,5,5));
 tx.setEditable(true);
 ts.setEditable(true);
 pack();
 setLocationRelativeTo(null);
 setVisible(true);
 }

public void paint(Graphics g)
{
 g.drawImage(im, 0,0,500,500, this);

}
class SampleWindowListener extends WindowAdapter
{
 public void windowClosing(WindowEvent e)
 {
 System.exit(0);
 }
}

class SampleActionListener implements ActionListener
{
 public void actionPerformed(ActionEvent e)
 {
 String tx= tx.getText();
 String ts= ts.getText();

 h=Integer.parseInt(tx);
 w=Integer.parseInt(ts);

 bt.setLabel("SENDED");
 add(lb);
 bt.setForeground(Color.green);
 bt.setFont(new Font("Serif", Font.BOLD,30));

 try {
 if(w/(h*2)<=18.5)
 {
 lb= new Label("�level1");
 add(lb);
 lb.setFont(new Font("Serif",Font.BOLD,20));
 setSize(600,400);
 setVisible(true);
 }
 else if(w/(h*2)>18.5 && w/(h*2)<=24.9)
 {
 lb= new Label("level2");
 add(lb);
 lb.setFont(new Font("Serif",Font.BOLD,20));
 setSize(600,400);
 setVisible(true);
 }
 else if(w/(h*2)>25 && w/(h*2)<=29.9)
 {
 lb= new Label("level3");
 add(lb);
 lb.setFont(new Font("Serif",Font.BOLD,20));
 setSize(600,400);
 setVisible(true);
 }
 else if(w/(h*2)>30 && w/(h*2)<=34.9)
 {
 lb= new Label("level4");
 add(lb);
 lb.setFont(new Font("Serif",Font.BOLD,20));
 setSize(600,400);
 setVisible(true);
 }
 else if(w/(h*2)>35 && w/(h*2)<=39.9)
 {
 lb= new Label("level5");
 add(lb);
 lb.setFont(new Font("Serif",Font.BOLD,20));
 setSize(600,400);
 setVisible(true);
 }
 else {
 lb= new Label("level6");
 add(lb);
 lb.setFont(new Font("Serif",Font.BOLD,20));
 setSize(600,400);
 setVisible(true);
 }
 }
 catch(ArrayIndexOutOfBoundsException a) {
 lb= new Label("nhap sai");
 add(lb);
 lb.setFont(new Font("Serif",Font.BOLD,20));
 setSize(600,400);
 setVisible(true);
 }
 }

 }

 }