Rule Definition
Due to rounding errors, most floating-point numbers end up being slightly imprecise. As long as this imprecision stays small, it can usually be ignored. However, it also means that numbers expected to be equal (e.g. when calculating the same result through different correct methods) often differ slightly, and a simple equality test fails.

Remediation
Except specific cases where we can expect that the value is the same (see http://randomascii.wordpress.com/2012/06/26/doubles-are-not-floats-so-dont-compare-them), the best is to compare the difference with Epsilon a small float number that you can configure according to the accuracy you want.

Violation Code Sample

float a = 0.15f + 0.15f;
float b = 0.1f + 0.2f;
if(a == b) {...} // VIOLATION
if(a != b) {...} // VIOLATION

Fixed Code Sample

static final float EPSILON = 0.0000001f;

float a = 0.15f + 0.15f;
float b = 0.1f + 0.2f;
if(Math.abs(a - b) < EPSILON) {...} // FIX
if(Math.abs(a - b) > EPSILON) {...} // FIX

Java Language Specification > 4.2.4. Floating-Point Operations: http://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.2.4 Doubles are not floats, so don't compare them: http://randomascii.wordpress.com/2012/06/26/doubles-are-not-floats-so-dont-compare-them/ What's wrong with using == to compare floats in Java? http://stackoverflow.com/questions/1088216/whats-wrong-with-using-to-compare-floats-in-java http://floating-point-gui.de/errors/comparison/