怎样用java编写一个程序，从键盘上输入数n，计算并输出1！+2！...+n!的结果

import java.awt.*; import java.awt.event.*; class MyDow extends Frame implements ActionListener{ private Label lName,lPassword; private TextField tName,tPassword; private Button login,rest,exitout; private Label login_clew; private int count=0; private St