关于Integer.parseInt()的问题，求高手指点

import java.awt.*;
import java.awt.event.*;

class YourWindow extends Frame implements ActionListener
{
    TextField text1,text2;
    PoliceMan police;
    YourWindow()
    {
        text1 = new TextField(10);
        text2 = new TextField(10);
        police = new PoliceMan();
        setLayout(new FlowLayout());
        add(text1);
        add(text2);
        text1.addActionListener(this);
        text1.addActionListener(police);
        setBounds(100,100,150,150);
        setVisible(true);
        validate();
    }
   
    public void actionPerformed(ActionEvent e)
    {
        String number = e.getActionCommand();
        int n = Integer.parseInt(number);
        int m = n*n;
        text2.setText(n+"的平方是"+m);
    }
}

class PoliceMan implements ActionListener
{
    public void actionPerformed (ActionEvent e)
    {
        String number = e.getActionCommand();
        int n = Integer.parseInt(number);
        int m =n*n;
        System.out.println(n+"的立方是"+m);
    }
}

public class Example7_4
{
    public static void main(String args[])
    {
        YourWindow win = new YourWindow();
    }
}