Re: Closing Files that Weren't Successfully Opened

From:

Michal Kleczek <kleku75@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 15 Mar 2011 12:09:15 +0000 (UTC)

Message-ID:

<ilnktb$v35$4@news.onet.pl>

On Tue, 15 Mar 2011 07:54:17 -0400, Lew wrote:

On 03/15/2011 06:53 AM, Michal Kleczek wrote:

On Tue, 15 Mar 2011 03:41:15 -0700, Robert Klemme wrote:

If you want BufferedReader you can do

final BufferedReader reader =
   new BufferedReader(new InputStreamReader(new
FileInputStream("foo.txt")));
try {
   for (String line; (line = reader.readLine()) != null;) {
     System.out.println("Found line: " + line);
   }
}
finally {
   reader.close();
}

That only works because both InputStreamReader and BufferedReader
constructors don't throw.
But it is not safe to do the same for: final ObjectInputStream ois =
new ObjectInputStream(new FileInputStream("foo.txt"));

That's covered upthread five and a half hours prior to the cited post.

Maybe I'm missing it but could not find anything related.
If you're talking about your post - there is still this
new BufferedReader(new ...) thingy hanging around there
and nothing about watching out for leaked resources if both
chained constructors can throw.

Sometimes it would be good to have destructors...

Nonsense. Destructors are to release memory.

Who told you that? :)

This is about external
resources.

And that is also something that destructors can (and should) release.
Please - google "RAII".

What Java needs are 'finally' blocks. Hey, good news! It's
got them! Yay! Problem solved!

The point is they are not really straightforward to use
and cause a lot of clutter in the code.
This is not only my opinion: introduction of "with" statement in C#,
proposed changes to Java 7 and this thread itself speak for themselves.

--
Michal