Question

I have expression:

Double getAbs(Double value){
return value> 0 ? value: value== 0 ? null : -value;
}

or better:

 Double getAbs(Double value){
return Math.abs(value);
}

I understand that there are some differences about NaN. But method Math.abs(double) – so we have unboxing.
In which case performance better?

Answer 1

The only “performance” in your code is that the JVM will need to unbox your Double to double.

Math.abs(double) uses a ternary if statement as follows:

public static double abs(double a) {
    return (a <= 0.0D) ? 0.0D - a : a;
}

So, your if statement is no performance worry at all.