请大家帮我编写一个java程序，急用，谢谢啦。题目如下

//很简陋的写了下

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

import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JTextField;

public class LongApp extends JApplet {

private JLabel l1 = new JLabel("输入数字: ");
private JTextField f = new JTextField();
private JButton b = new JButton("分解");
private JLabel l2 = new JLabel();
@Override
public void init() {
super.init();
this.setLayout(null);
this.setBounds(200, 200, 800, 600);
l1.setLocation(60, 60);
l1.setSize(100, 20);
f.setBounds(180, 60, 200, 20);
b.setLocation(460, 60);
b.setSize(100, 20);
l2.setSize(400, 200);
l2.setLocation(150, 60);
b.addActionListener(new ActionListener(){
@Override
public void actionPerformed(ActionEvent e) {
char [] cs = f.getTex