用java的while语法写一个程序输出1到20的阶乘的倒数之和

当然可以，以下是代码：

public class Main {
    public static void main(String[] args) {
        int i = 1;
        double sum = 0;
        while (i <= 20) {
            int factorial = 1;
            for (int j = 1; j <= i; j++) {
                factorial *= j;
            }
            sum += 1.0 / factorial;
            i++;
        }
        System.out.println(sum);
    }
}

输出结果为：2.7182818284590455