exists and notExists

[Elliotte Harold]

Alan Bateman wrote:

>> (If not, the JavaDoc needs to be clarified.)
> If the javadoc isn't clear then we can improve it. In this case it says 
> it returns false "if the file does not exist or its existence cannot be 
> determined".
> 

But what is gained? I still don't understand in what circumstances 
notExists() will tell you something that !exists() does not. Can you 
please clarify when

!path.exists() might return a different answer than path.notExists()?

Might they both return false if the existence cannot be determined?

If so, I'd argue that the non-Aristotelian logic here is likely to be 
deeply confusing. (It's certainly confusing me.) Better solutions would 
be to either

1. Use an enumerated return type rather than a boolean that has three 
states: exists, not exists, unknown.

or

2. Throw an IOException if the existence cannot be determined.

I'm not sure which I prefer. I think #2 is probably easier, but I'm not 
sure of that. Regardless the current scheme is just asking for confusion.

-- 
Elliotte Rusty Harold  elharo at metalab.unc.edu
Java I/O 2nd Edition Just Published!
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