如何在Java中扩展BigDecimal？

Question

import java.math.*;

class Moqueet {
    public static void main(String [] args){
        double a, b, c;
        BigDecimal bg1, bg2;
        a = 1;
        b = 10000;
        c = a / b;
        bg1 = new BigDecimal(c);
        MathContext mc = new MathContext(10);
        bg2 = bg1.round(mc);
        System.out.println(bg1);
    }
    }

当我尝试这个时，我得到如下输出：

0.000100000000000000004792173602385929598312941379845142364501953125

我希望我的出局仅为0.0001。我怎么能得到这个？

Answer 1

 bg1 = bg1.setScale(4, RoundingMode.FLOOR);