Java Double NaN comparison for sort

Question

I'm implementing Comparator for a class and while overriding the compare , i have a question.

double data1 = GetValueOf(Data1);
double data2 = GetValueOf(Data2);
int compareResult = Double.compare(data1, data2);

What happens if data1 and/or data2 are NaN?

Is this still a valid comparison to perform?

UPDATE I don't understand why this question is being down rated. Just to explain myself, I'm facing a " Comparison method violates general contract " problem.

I'm doing this...

if(Double.isNaN(data1)) data1 = Double.Positive_Infinity;
if(Double.isNaN(data2)) data2 = Double.Positive_Infinity;

before the Double.compare but still getting this error.

So, I need to understand if there's some basic thing I'm not understanding.

Answer 1

An unordered result is result is returned if you are comparing NAN with itself. The Java document says:

An operation that overflows produces a signed infinity, an operation that underflows produces a denormalized value or a signed zero, and an operation that has no mathematically definite result produces NaN. All numeric operations with NaN as an operand produce NaN as a result. As has already been described, NaN is unordered, so a numeric comparison operation involving one or two NaNs returns false and any != comparison involving NaN returns true, including x!=x when x is NaN.