Java编程之求输入数的阶乘

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
class Factor implements ActionListener
{
JTextArea jta=new JTextArea(1,15);
JFrame frame=new JFrame("Çó½×³Ë");
Factor()
{

JButton OK=new JButton("Ok");
OK.addActionListener(this);
JButton Cancel=new JButton("Cancel");
Cancel.addActionListener(this);
JButton Clear=new JButton("Clear");
Clear.addActionListener(this);
frame.getContentPane().setLayout(new FlowLayout());
frame.getContentPane().add(jta);
frame.getContentPane().add(OK);
frame.getContentPane().add(Cancel);
frame.getContentPane().add(Clear);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.show();
frame.setSize(300,250);
frame.setLocation(400,200);
}
public static void main(String[] args)
{
Factor fac=new Factor();