Search code examples
javaprecisionbigdecimal

BigDecimal failed to set precision of 8 digits during multiplication

I am trying make a multiplication of a BigDecimal number with a precision of 8 digits

Here is what I want to take

0.02749639

This is my code

double amount = 2120;
double BuyPrice = 0.00001297;
BigDecimal result=BigDecimal.valueOf(BuyPrice).multiply(BigDecimal.valueOf(amount)).setScale(8,RoundingMode.HALF_DOWN);
System.out.println(result);

and here what did I took

0.027496400

Can someone help me to fix it?

Solution

  • 0.0274964 is the right result. Perhaps in some other part of your code you have already lost precision due to using double?

    When you use BigDecimal.valueOf(double) you are experiencing a precision loss when you declare the double. To avoid it one should use new BigDecimal(String) constructor:

    BigDecimal d1 = BigDecimal.valueOf(90.000000000000001d);
BigDecimal d2 = BigDecimal.valueOf(90.000000000000002d);
System.out.println(d1.equals(d2));

BigDecimal s1 = new BigDecimal("90.000000000000001");
BigDecimal s2 = new BigDecimal("90.000000000000002");
System.out.println(s1.equals(s2));

    Will print

    true
false