== Why is this an issue?

The `BigDecimal` is used to represents immutable, arbitrary-precision signed decimal numbers.

Differently from the `BigDecimal`, the `double` primitive type and the `Double` type have limited precision
due to the use of double-precision 64-bit IEEE 754 floating point. Because of floating point imprecision,
the `BigDecimal(double)` constructor can be somewhat unpredictable.

For example writing `new BigDecimal(0.1)` doesn't create a BigDecimal which is exactly equal to 0.1,
but it is 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).

== How to fix it

Use `BigDecimal.valueOf`, which uses a string under the covers to eliminate floating point rounding errors,
or the constructor that takes a `String` argument.

=== Code examples

==== Noncompliant code example

[source,java,diff-id=1,diff-type=noncompliant]
----
double d = 1.1;

BigDecimal bd1 = new BigDecimal(d);   // Noncompliant
BigDecimal bd2 = new BigDecimal(1.1); // Noncompliant
----

==== Compliant solution

[source,java,diff-id=1,diff-type=compliant]
----
double d = 1.1;

BigDecimal bd1 = BigDecimal.valueOf(d); // Compliant
BigDecimal bd2 = new BigDecimal("1.1"); // Compliant
----

== Resources

=== Documentation

* https://docs.oracle.com/en/java/javase/20/docs/api/java.base/java/math/BigDecimal.html[Oracle - BigDecimal]
* https://wiki.sei.cmu.edu/confluence/x/kzdGBQ[CERT, NUM10-J] - Do not construct BigDecimal objects from floating-point literals

ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
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=== Message

Use "BigDecimal.valueOf" instead.


'''
== Comments And Links
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=== on 7 Oct 2014, 16:24:30 Nicolas Peru wrote:
\[~ann.campbell.2] we might want to refer or quote the JavaDoc of BigDecimal double constructor here : \http://docs.oracle.com/javase/7/docs/api/java/math/BigDecimal.html#BigDecimal(double) 

=== on 10 Oct 2014, 15:13:53 Freddy Mallet wrote:
Perfect !

=== on 16 Jan 2015, 09:32:59 Sébastien Gioria wrote:
Coudl be tag "security" as it's part of the CERT Secure Coding for Java (\https://www.securecoding.cert.org/confluence/display/java/NUM10-J.+Do+not+construct+BigDecimal+objects+from+floating-point+literals)



=== on 19 Jan 2015, 08:42:15 Ann Campbell wrote:
Thanks [~sebastien.gioria], reference added!

=== on 14 Jul 2016, 16:04:49 Ann Campbell wrote:
https://github.com/google/error-prone/blob/master/docs/bugpattern/BigDecimalLiteralDouble.md

endif::env-github,rspecator-view[]
