CODEWITHSUNDEEP
javajsongsonbigdecimal
vatsal mevada
vatsal mevada

Reputation: 5616

Serializing BigDecimal value using GSON

here is my code:

System.out.println(GSON.toJson(new BigDecimal(10.12)));

and the output is: 

10.1199999999999992184029906638897955417633056640625

Is it possible to limit the precision of BigDecimal value that GSON serialize? i.e. my expected output of serialized value is: 

10.11

Upvotes: 4

Views: 10834

Answers (2)

cнŝdk
cнŝdk

Reputation: 32145

The problem here isn't with GSON but with your BigDecimal value instead.

If you use the new BigDecimal(double value) constructor you can have unpredictable results.

If you take a look at BigDecima(double value) constructor documentation it clearly says :

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.

So it's better to use the BigDecimal String constructor here:

new BigDecimal("10.12")

Upvotes: 8

Raman Sahasi
Raman Sahasi

Reputation: 31841

This is not a GSON issue. new BigDecimal() try to represent double accurately and ends up taking lot more digits.

You can use BigDecimal.valueOf(10.12) or new BigDecimal("10.12") instead of new BigDecimal().

System.out.println(GSON.toJson(BigDecimal.valueOf(10.12)));

Upvotes: 2

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