Re: The first 10 files
On 1/26/2013 8:56 PM, Peter Duniho wrote:
On Sat, 26 Jan 2013 20:42:16 -0500, Eric Sosman wrote:
[...]
Because the listFiles() method will fetch the information
for all 30K files from the O/S, will construct 30K File objects
to represent them, and will submit all 30K File objects to the
FileFilter, one by one. The FileFilter will (very quickly)
reject 29.99K of the 30K Files, but ...
Will it?
Necessarily. As far as listFiles() knows, the FileFilter
might accept the very last File object given to it. Therefore,
listFiles() cannot fail to present that very last File -- and
every other File -- for inspection.
Except in the way I already noted, you mean.
Except if the code was different from the code he was
commenting on.
[...]
Indeed, I suppose one could throw an exception from the FileFilter accept()
method to interrupt enumeration, if that's how listFiles() is implemented.
That would avoid the need to enumerate more than the needed number of
actual files.
It would also avoid the burden of returning anything from
listFiles() -- like, say, the array of accepted files ...
As you've already agreed, it is possible for the FileFilter implementation
to store the results itself, obviating any need for the listFiles() method
to return successfully.
If it works (which is not assured...it depends on how listFiles() is
implemented in the first place), then yes, maybe it's a bit of a kludge.
But it's an easier, more portable kludge than writing some JNI-based
component and would in fact get the job done.
Sometimes, when the library you're using doesn't provide exactly the
features you need, you wind up with a kludge. Oh well...shit happens.
If JNI is used then at least it is straight forward logic.
Utilizing Java library classes in a way that they were not intended
to be used based on as assumption about the underlying implementation
is not straight forward logic.
I'm not saying it's a great solution. But it's a far cry from a conclusion
that it simply cannot be done with the Java API as it exists now.
There is no way in Java API to ensure that it will be done.
We just find it likely that then implementation will work
that way.
Arne