Re: (File)OutputStreams and their usage
Philipp wrote:
Leonard Milcin wrote:
Philipp wrote:
Dear all,
Is this (see code) the correct way of handling a
FileOutputStream? Specific question are in the code. Thanks for
your answers. Philipp
public void load(File file){ OutputStream os; try { os = new
FileOutputStream(file); } catch (Exception e) { logger.log("Could
not open file output stream", e); // can os be non-null here? //
should I put a close() here? return; }
try { load(os); // call of another load method with OutputStream
} catch (Exception e) { logger.log("Exception while loading from
file.", e); return; // is this return of any interest? }
finally { if(os != null){ try { os.close(); } catch (Exception e)
{ // exception while closing, what can we do? } } } }
Well, you're converting from exceptions to error codes. load() can
silently fail and it's up to the caller to check if it has loaded
anything. I would propagate exceptions or convert them to another
type of exception.
Yes, you are correct, I should definitely rethrow rather than log at
that point. But this was not really my question. I'm rather asking at
what points I I have to call close() on the stream to gurantee
correct release of resources in all cases and whether having a return
in the first or second catch is problematic in this respect. Phil
public void load(File file) throws ... {
OutputStream os;
try {
os = new FileOutputStream(file);
load(os);
} finally {
if (os!=null) {
os.close();
}
}
}
That looks much cleaner. The caller has to deal with all those checked
excetions, though. You can convert to another type of exception (like
unchecked exception).
The reason why I don't surround os.close() with try/catch is that
usually it should not throw exception but if it does... I would
certainly want to know. Besides, load(os) probably also throws
IOException and nested try/catch looks too ugly for my taste...
When it goes to logging you should do logging only when you deal with
exception. Perhaps also when it crosses some boundary (like library,
layer, etc.) but, personally, I don't like it.
Regards,
Leonard
--
Simplicity is the ultimate sophistication.
-- Leonardo da Vinci