How to round decimal part of number so it doesn't affect whole the part of number?

Question

I have this BigDecimal number - 68.65121847597993 and I want to round it like this - 68.7, so only decimical part of number would be rounded up, but not the whole number.

I tried to use RoundingMode.HALF_UP but it rounds up the whole number as well. Is there a way to round up only decimical part of number using java?

Answer 1

In order to represent a number with that many decimal points, I presume you are using BigDecimal rather than double, which can only accurately represent approximately 15 significant digits.

Starting from a BigDecimal, which you can initialize with a string, a double, or anything else you have, you can call BigDecimal::setScale to get the value you want.

For example:

import java.math.*;

public class HelloWorld {
  public static void main(String []args){
    BigDecimal b = new BigDecimal("68.65121847597993");
    BigDecimal rounded = b.setScale(2, RoundingMode.HALF_UP);
    System.out.println(rounded);  // 68.65
  }
}