CODEWITHSUNDEEP
javadouble
xMilos
xMilos

Reputation: 2018

java decimal format not rounding correctly

I have this code

private static DecimalFormat df2 = new DecimalFormat(".00");
System.out.println(df2.format(14.3445));

the correct answer for this should be 14.35 but i get 14.34 Why ?

The conversion should be 14.3445 -> 14.345 -> 14.35

Upvotes: 0

Views: 137

Answers (2)

Mohl
Mohl

Reputation: 415

14.34 is correct, as it is closer to 14.3445 that 14.35:

|14.3445 - 14.34| = 0.0045

while

|14.3445 - 14.35| = 0.0055

Upvotes: 3

Timothy Truckle
Timothy Truckle

Reputation: 15622

from the API https://docs.oracle.com/javase/8/docs/api/java/text/DecimalFormat.html

Rounding

DecimalFormat provides rounding modes defined in RoundingMode for formatting. By default, it uses RoundingMode.HALF_EVEN.

and https://docs.oracle.com/javase/8/docs/api/java/math/RoundingMode.html#HALF_EVEN

public static final RoundingMode HALF_EVEN

Rounding mode to round towards the "nearest neighbor" unless both neighbors are equidistant, in which case, round towards the even neighbor. Behaves as for RoundingMode.HALF_UP if the digit to the left of the discarded fraction is odd; behaves as for RoundingMode.HALF_DOWN if it's even.

Since the second 4 (third fraction digit) is even it is not changed which leads to "round down" for the second fraction digit.

Upvotes: 2

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