Buffering streams and writers...

[Spencer Lee]

Hello,

I wondering if there is an advantage to wrapping streams with BufferedOutputStream before passing it to OutputStreamWriter over simply wrapping the OutputStreamWriter with a BufferedWriter? Or is it better to do both?

For example, whats the best practice...

1)

new PrintWriter(
  new BufferedWriter(
    new OutputStreamWriter(
      new BufferedOutputStream( <SOME SORT OF OUTPUT STREAM OBJECT> ))));

2)

new PrintWriter(
  new OutputStreamWriter(
    new BufferedOutputStream( <SOME SORT OF OUTPUT STREAM OBJECT> )));

3)

new PrintWriter(
  new BufferedWriter(
      new OutputStreamWriter( <SOME SORT OF OUTPUT STREAM OBJECT> )));

Thanks,
Spencer
[ December 06, 2005: Message edited by: Spencer Lee ]

[Joe Ess]

Originally posted by Spencer Lee:
Hello,
I wondering if there is an advantage to wrapping streams with BufferedOutputStream before passing it to OutputStreamWriter over simply wrapping the OutputStreamWriter with a BufferedWriter?

There is probably no difference because the buffer sizes for BufferedWriter and BufferedOutputStream are the same (8k in JDK 1.5.0). Wrapping a buffered stream with a buffered writer would not get you any positive benefit for the same reason.
Since tweaking IO throughput is very application-dependent, you should look at Java Platform Performance - IO for the details on IO performance and how to measure and test it.

[Spencer Lee]

Thank you Joe. I'll check out your link.

[Paul Clapham]

There is probably no difference because the buffer sizes for BufferedWriter and BufferedOutputStream are the same...

However if you are using a charset where more than one byte is frequently converted to a single char, then the boundaries of the two buffers aren't going to match up so nicely any more. Whether this matters I have no idea, though.

Personally I would expect that a buffer between disk and memory would produce more benefits than a buffer between memory and memory. But then I distrust that kind of "explanation", so I would produce the "It depends, try it and see" sort of answer too.