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According to The Java Language Specification (JLS), §4.2.3, "Floating-Point Types, Formats, and Values" [JLS 20052015]:

NaN (not-a-number) is unordered, so the numerical comparison operators <, <=, >, and >= return false if either or both operands are NaN. The equality operator == returns false if either operand is NaN, and the inequality operator != returns true if either operand is NaN.

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This noncompliant code example attempts a direct comparison with NaN. In accordance with the semantics of NaN, all comparisons with NaN yield false (with the exception of the != operator, which returns true). Consequently, this comparison always return false, and the "result is NaN" message is never printed.

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[FindBugs 2008]	FE: Doomed test for equality to NaN
[JLS 20052015]	§4.2.3, "Floating-Point Types, Formats, and Values"
[Seacord 2015]	NUM07-J. Do not attempt comparisons with NaN LiveLesson

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