求教java身高体重互查程序,该怎么解决

求教java身高体重互查程序
请教高人:

编写成人标准身高和体重互查程序。身高和体重在两个不同的文本框中输入,要求输入一个,输出另一个。用一个按钮启动互查。
  互查公式为: 体重=身高-100

我编写的程序如下:可是输入体重就会出现问题是怎么回事啊!!!
  import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class HeightWeight implements ActionListener
{
JTextField tf1=new JTextField(10);
JTextField tf2=new JTextField(10);

HeightWeight()
{
GUI();
}
void GUI()
{
JFrame myframe=new JFrame("身高与体重查询");
myframe.setLayout(new FlowLayout(FlowLayout.CENTER));

JPanel p1=new JPanel();
JPanel p2=new JPanel();
JPanel p3=new JPanel();

JLabel label1=new JLabel("身高");
JLabel label2=new JLabel("体重");

//JTextField tf1=new JTextField(10);
tf1=new JTextField(10);
//JTextField tf2=new JTextField(10);
tf2=new JTextField(10);

JButton button=new JButton("转换");
button.addActionListener(this);

p1.add(label1);
p1.add(tf1);

p2.add(label2);
p2.add(tf2);

p3.add(button);

myframe.getContentPane().add(p1);
myframe.getContentPane().add(p2);
myframe.getContentPane().add(p3);
myframe.setSize(200,300);
myframe.setVisible(true);
}
public void actionPerformed(ActionEvent e)
{
String t=tf1.getText().toString();
int x=Integer.parseInt(t);
Integer h=x-100;
String u=Integer.toString(h);
tf2.setText(u);
String s=tf2.getText().toString();
int y=Integer.parseInt(s);
Integer l=y+100;
String v=Integer.toString(l);
tf1.setText(v);


}
public static void main(String[] args)
{
new HeightWeight();
}

}


------解决方案--------------------
Java code

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class HeightWeight implements ActionListener
{
    JTextField tf1=new JTextField(10);
    JTextField tf2=new JTextField(10);

    HeightWeight()
    {
        GUI();
    }
    public void GUI()
    {
        JFrame myframe=new JFrame("身高与体重查询");
        myframe.setLayout(new FlowLayout(FlowLayout.CENTER));

        JPanel p1=new JPanel();
        JPanel p2=new JPanel();
        JPanel p3=new JPanel();

        JLabel label1=new JLabel("身高");
        JLabel label2=new JLabel("体重");

//JTextField tf1=new JTextField(10);
        tf1=new JTextField(10);
//JTextField tf2=new JTextField(10);
        tf2=new JTextField(10);

        JButton button=new JButton("转换");
        button.addActionListener(this);

        p1.add(label1);
        p1.add(tf1);

        p2.add(label2);
        p2.add(tf2);

        p3.add(button);

        myframe.getContentPane().add(p1);
        myframe.getContentPane().add(p2);
        myframe.getContentPane().add(p3);
        myframe.setSize(200,300);
        myframe.setVisible(true);
        myframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    public void actionPerformed(ActionEvent e)
    {
        String t=tf1.getText().trim();
        if(!t.isEmpty()){
            int x=Integer.parseInt(t);
            Integer h=x-100;
            String u=Integer.toString(h);
            tf2.setText(u);
        }

        String s=tf2.getText().trim();
        if(!s.isEmpty()){
            int y=Integer.parseInt(s);
            Integer l=y+100;
            String v=Integer.toString(l);
            tf1.setText(v);
        }



    }
    public static void main(String[] args)
    {
        new HeightWeight();
    }

}