Re: On exceptions

From:

Twisted <twisted0n3@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

25 May 2007 11:51:02 -0700

Message-ID:

<1180119062.885224.168950@q75g2000hsh.googlegroups.com>

On May 25, 8:39 am, dvdsum <davide.sammart...@gmail.com> wrote:

In java we have exceptions, which are too generic and are associated
with different errors. For example:

PipedInputStream read method throws an IOException if input is not
connected with an output stream, or pipe is closed or other IO errors.
Now, form the block catch(IOException e) how can I know the exact
error?

You can catch a specific subclass of IOException to trap on more
specific conditions and distinguish among them. Go to IOException in
the javadoc and then look at the "known subclasses" and their known
subclasses, etc. to get a picture of what you can trap. You should
still catch any remaining IOExceptions and deal with them somehow,
though:

FooStream something = null;
try {
something = somethingElse.openStream();
....
} catch (FileNotFoundException e) {
// It's missing!
....
} catch (SocketException e) {
// Network problem!
....
} catch (IOException e) {
// Something else went wrong!
....
} finally {
if (something != null) something.close();
}