How to round the double value in Java

Question

I have tried to make the double value as round to the 2 precision values.I got it by using Date Format, but it is in String. How to make the double value as round to the precision without using Date Format.

Do you want to round the printed value (for display purposes) or the variable itself (for calculation purposes) — Richard Tingle, Oct 16 '13 at 07:15
share your scenario plz , do you want something like this ??http://stackoverflow.com/a/12190890/1283215 — Hussain Akhtar Wahid 'Ghouri', Oct 16 '13 at 07:16
Maybe BigDecimal is your choise? Doubles are not very good with true rounding. — Leonidos, Oct 16 '13 at 07:19

score 1 · Answer 1 · answered Oct 16 '13 at 07:20

here is the example

public class RoundValue 
{
    public static void main(String[] args)
    {   

    double kilobytes = 1205.6358;

    System.out.println("kilobytes : " + kilobytes);

    double newKB = Math.round(kilobytes*100.0)/100.0;
    System.out.println("kilobytes (Math.round) : " + newKB);

    DecimalFormat df = new DecimalFormat("###.##");
    System.out.println("kilobytes (DecimalFormat) : " + df.format(kilobytes));
    }
}

output:

kilobytes : 1205.6358
kilobytes (Math.round) : 1205.64
kilobytes (DecimalFormat) : 1205.64

Does not round, so not an answer, and the technique [does not work in general](http://stackoverflow.com/a/12684082/207421). — user207421, Oct 16 '13 at 08:50

score 0 · Answer 2 · edited May 23 '17 at 12:28

As EJP and Leonidos said in comments, proper rounding is performed through the BigDecimal class not the double primitive.

Carefully choose your rounding mode. Banker's Rounding is a common way to break ties (even splits), though the best way depends on your purpose and situation.

double d = 7.345;
java.math.BigDecimal bigDecimal = new java.math.BigDecimal(d).setScale(2, java.math.RoundingMode.HALF_EVEN);
System.out.println("My big decimal is: " + bigDecimal ); // Outputs: 7.34 (using Banker's Rounding)

See: How to round a number to n decimal places in Java

How to round the double value in Java

2 Answers2