JAVA語法——使用while循環計算階乘

package 使用while循環計算階乘;

import java.math.*;
public class 使用while循環計算階乘 {
    
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        BigDecimal sum = new BigDecimal(0.0);
        BigDecimal factorial = new BigDecimal(1.0);
        
        int i = 1;
        
        while(i <= 20)
        {
            sum = sum.add(factorial);
            ++i;
            factorial = factorial.multiply(new BigDecimal(1.0/i));
        }
        
        System.out.println("1+1/2!+1/3!+...+1/20!的計算結果等於:\n"+sum);
    }

}