Re: TeeOutputStream?

From:
Henk van Voorthuijsen <voorth@gmail.com>
Newsgroups:
comp.lang.java.help
Date:
Wed, 8 Jun 2011 03:31:02 -0700 (PDT)
Message-ID:
<db77bbe4-6a43-4c1d-8929-8a637a599eb6@m10g2000yqd.googlegroups.com>
On Jun 5, 2:17 am, Knute Johnson <nos...@knutejohnson.com> wrote:

I'm working on a project where I need to send the same data to two
OutputStreams so I went snooping around on the net for some code to
snatch. Most of the examples I found had what I think is a significant
flaw. That is if for example the write() method looks like this;

public void write(byte b) throws IOException {
     os1.write(b);
     os2.write(b);

}

if OutputStream os1 throws an IOException, no attempt to write the data
to os2 will happen. This probably isn't too big a concern for writes
but what about close()?

public void close() throws IOException {
     os1.close();
     os2.close();

}

If os1 throws an IOException on the close() method, then os2's close()
method will never get executed possibly leaving the stream open and the
attached resources still around. What about;

public void close() throws IOException {
     try {
         os1.close();
     } finally {
         os2.close();
     }

}

This guarantees that both close() methods will get called. If both
methods throw IOExceptions the caller will never see the first one as it
will be hidden.

What do you think? Have I completely over thought this?


You might want to wait for JDK 7's "try with resources" feature. All
your concerns have been addressed there - im much more detail.

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