java中用while循环计算1+1/2!+1/3!+...+1/20!之和

Answer 1

public class Example_02 {
public static void main(String args[])

{
double sum = 0,a = 1;
int i = 1;
while(i <= 20)
{
sum = sum+a;
i = i+1;
a = a*(1.0/i);
}
System.out.println(sum);
}
}