Operators and Expressions - The Java Programming Language - page 305

greater than or equal to

>=

less than

<

less than or equal to

<=

equal to

==

not equal to

!=

Both the relational and equality operators can be applied to the primitive
numeric types, with the usual mathematical interpretation applying.

Floating-point values follow normal ordering (1.0 is less than 0.0 is less
than positive infinity) except that NaN is an anomaly. All relational and
equality operators that test a number against NaN return false , except
!= , which always returns true . This is true even if both values are NaN.
For example,

Double.NaN == Double.NaN

is always false . To test whether a value is NaN, use the type-specific
NaN testers: the static methods and

Float.isNaN(float)

Double.isNaN(double) . [2]

[2] There is one other way to test for NaN: If x has a NaN value, then x != x is true. This is interesting
but very obscure, so you should use the methods instead.