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); } } !为阶乘 求解释 a = a*(1.0/i); 这串代码什么意思 真没看懂 就解释这一条就行