long primitive NaN value wanted

Scenario:

1) I have a long state variable that can either be set or not set.

2) This long variable has valid values from Long.MIN_VALUE to Long.MAX_VALUE including zero

3) This is performance sensitive code so I don't want to use a Long wrapper type

How do I write an 'is set' kind of check for this long? Do I really have to add a second boolean value to test whether the long is valid or not? This seems sloppy. I know I could use a Long wrapper here but this seems like a performance waste to be creating so many objects and checking for null.

Pseudo Code (this is sort of what I want):

class foo {
long someLong = NaN; //NaN = hypothetical not a number like Double
public reset() { someLong = NaN;
}
public doSomethingElse() { if(someLong !=NaN) { //report reset(); }
}
public doSomeStuff() { if(someLong == NaN) { someLong = //something }
}
}
}

4 Answers

You'd have to set aside a special value for NaN. If you really use all possible values, there is none.

Are you sure Long objects are that much of a performance problem?

If so, maybe have an extra boolean to denote if the value is set or not?

Use a Long instead of a long, and use null as the NaN value.

There is no NaN for a long. If you're sure that performance is critical (I'd test the speed penalty of using a Long), then you'll want to use another flag value.

I have used Long.MIN_VALUE as its has odd properties like

Long.MIN_VALUE == -Long.MIN_VALUE

Its also less likely to occur naturally.

The problem with using it is, it can make the code more complex. For this reason I have use double instead integer values less than +/- 2^53 can be represented without error.