编写一个Application程序，求1！+2！+3！+ … +20!

//test.java
import java.util.*;
import java.lang.*;
public class test{
public long method(int i){
long sum=1;
int j;
for(j=1;j<=i;j++)
sum=sum*j;
return sum;
}//计算i的阶乘
public void main(String args[]){
int i,b;
long sum=0;
Scanner sc=new Scanner();
test tst=new test();
System.out.println("请输入数值上限：");
i=sc.nextInt();
for(b=1;b<=i;b++)
sum=sum+tst.method(b);//计算总值
System.out.println("结果是："+sum);

}
}