rspec/rules/S2185/java/rule.adoc

== Why is this an issue?

Some mathematical operations are unnecessary and should not be performed because their results are predictable.

For instance, `anyValue % 1` will always return 0, as any integer value can be divided by 1 without remainder.

Similarly, casting a non-floating-point to a floating-point value and then passing it to `Math.round`, `Math.ceil`, or `Math.floor` is also unnecessary, as the result will always be the original value.

The following operations are unnecessary when given any constant value: `Math.abs`, `Math.ceil`, `Math.floor`, `Math.rint`, `Math.round`.
Instead, use the result of the operation directly.

The following operations are unnecessary with certain constants and can be replaced by the result of the operation directly:

[frame=all]
[cols="^1,^1"]
|===
|Operation|Value

|acos|0.0 or 1.0
|asin|0.0 or 1.0
|atan|0.0 or 1.0
|atan2|0.0
|cbrt|0.0 or 1.0
|cos|0.0
|cosh|0.0
|exp|0.0 or 1.0
|expm1|0.0
|log|0.0 or 1.0
|log10|0.0 or 1.0
|sin|0.0
|sinh|0.0
|sqrt|0.0 or 1.0
|tan|0.0
|tanh|0.0
|toDegrees|0.0 or 1.0
|toRadians|0.0
|===

== How to fix it

Ask yourself if the questionable operation represents the desired calculation or if a value used is erroneous.
If the calculation is correct, replace it with the result to avoid having to perform the unnecessary operation at runtime.

=== Code examples

==== Noncompliant code example

[source,java,diff-id=1,diff-type=noncompliant]
----
public void doMath(int a) {
  double res1 = Math.floor((double)a); // Noncompliant, the result will always be equal to '(double) a'
  double res2 = Math.ceil(4.2);        // Noncompliant, the result will always be 5.0
  double res3 = Math.atan(0.0);        // Noncompliant, the result will always be 0.0
}
----

==== Compliant solution

[source,java,diff-id=1,diff-type=compliant]
----
public void doMath(int a) {
  double res1 = a;    // Compliant
  double res2 = 5.0;  // Compliant
  double res3 = 0.0;  // Compliant
}
----

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

'''
== Implementation Specification
(visible only on this page)

=== Message

Remove this unnecessary call to "Math.xxx".


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