用java求1+1/2!+1/3!+1/4!…+1/20!的和。

以下是Java代码实现：

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

输出结果为：1.7182818284590455