CODEWITHSUNDEEP
javabigdecimal
Vishal Zanzrukia
Vishal Zanzrukia

Reputation: 4973

BigDecimal behavior in Java

public class Test {
    public static void main(String[] args){
         System.out.println(new BigDecimal(58.34));
    }
}

If I run above given program in Java, it is giving me output like: 58.340000000000003410605131648480892181396484375

Why is it?

Upvotes: 0

Views: 95

Answers (3)

Ankur Singhal
Ankur Singhal

Reputation: 26067

I think the BigDecimal.java best explains this feature.

API say's

Translates a double into a BigDecimal which is the exact decimal representation of the double's binary floating-point value. The scale of the returned BigDecimal is the smallest value such that (10scale × val) is an integer.

Notes:

The results of this constructor can be somewhat unpredictable. One might assume that writing new BigDecimal(0.1) in Java creates a BigDecimal which is exactly equal to 0.1 (an unscaled value of 1, with a scale of 1), but it is actually equal to 0.1000000000000000055511151231257827021181583404541015625. This is because 0.1 cannot be represented exactly as a double (or, for that matter, as a binary fraction of any finite length). Thus, the value that is being passed in to the constructor is not exactly equal to 0.1, appearances notwithstanding.

The String constructor, on the other hand, is perfectly predictable: writing new BigDecimal("0.1") creates a BigDecimal which is exactly equal to 0.1, as one would expect. Therefore, it is generally recommended that the String constructor be used in preference to this one.

When a double must be used as a source for a BigDecimal, note that this constructor provides an exact conversion

Upvotes: 2

Ruchira Gayan Ranaweera
Ruchira Gayan Ranaweera

Reputation: 35547

This will cause due to double value

 System.out.println(new BigDecimal(58.34));
                                    ^^^

To avoid this you can use String value

 System.out.println(new BigDecimal("58.34"));

Upvotes: 3

Elliott Frisch
Elliott Frisch

Reputation: 201429

You pass a double when you construct the BigDecimal so the precision is already lost. Easiest fix is probably something like

System.out.println(new BigDecimal("58.34"));

Output is

58.34

Upvotes: 4

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