Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.java.programmer > #8419 > unrolled thread

Creating a PrintWriter with BufferedWriter versus just File

Back to article view | Back to comp.lang.java.programmer

Contents

  Creating a PrintWriter with BufferedWriter versus just File KevinSimonson <kvnsmnsn@hotmail.com> - 2011-09-30 10:00 -0700
    Re: Creating a PrintWriter with BufferedWriter versus just File Lew <lewbloch@gmail.com> - 2011-09-30 12:55 -0700
    Re: Creating a PrintWriter with BufferedWriter versus just File Arne Vajhøj <arne@vajhoej.dk> - 2011-09-30 21:30 -0400
    Re: Creating a PrintWriter with BufferedWriter versus just File Roedy Green <see_website@mindprod.com.invalid> - 2011-10-01 05:06 -0700
      Re: Creating a PrintWriter with BufferedWriter versus just File Arne Vajhøj <arne@vajhoej.dk> - 2011-10-01 15:53 -0400

#8419 — Creating a PrintWriter with BufferedWriter versus just File

What's the difference between this code:

PrintWriter destination
          = new PrintWriter
              ( new BufferedWriter( new FileWriter( new File( arg))));

and this code:

PrintWriter destination = new PrintWriter( new File( arg));

Do I get buffered output with the first code that I don't get with the
second code?  Or do I get the same buffered behavior with both?

Kevin Simonson

[toc] | [next] | [standalone]

#8425

KevinSimonson wrote:
> What's the difference between this code:
> 
> PrintWriter destination
>           = new PrintWriter
>               ( new BufferedWriter( new FileWriter( new File( arg))));
> 
> and this code:
> 
> PrintWriter destination = new PrintWriter( new File( arg));
> 
> Do I get buffered output with the first code that I don't get with the
> second code?  Or do I get the same buffered behavior with both?

No, the write semantics differ between the two.  In the BufferedWriter version, writes to the underlying stream occur only when the BufferedWriter buffer fills.  With the second form, writes occur every time the PrintWriter writes.  There is nothing in the documentation of PrintWriter
<http://download.oracle.com/javase/7/docs/api/java/io/PrintWriter.html>
to indicate that it buffers writes.  So it seems unlikely that you would "get the same buffered behavior with both".

-- 
Lew

[toc] | [prev] | [next] | [standalone]

#8431

On 9/30/2011 1:00 PM, KevinSimonson wrote:
> What's the difference between this code:
>
> PrintWriter destination
>            = new PrintWriter
>                ( new BufferedWriter( new FileWriter( new File( arg))));
>
> and this code:
>
> PrintWriter destination = new PrintWriter( new File( arg));
>
> Do I get buffered output with the first code that I don't get with the
> second code?  Or do I get the same buffered behavior with both?

You can lookup the classes in the Java docs.

If the docs does not say that class XYZ does ABC, then
you should not rely on class XYZ doing ABC even though
a specific implementation may do it.

Arne

[toc] | [prev] | [next] | [standalone]

#8438

On Fri, 30 Sep 2011 10:00:55 -0700 (PDT), KevinSimonson
<kvnsmnsn@hotmail.com> wrote, quoted or indirectly quoted someone who
said :

>What's the difference between this code:
>
>PrintWriter destination
>          = new PrintWriter
>              ( new BufferedWriter( new FileWriter( new File( arg))));
>
>and this code:
>
>PrintWriter destination = new PrintWriter( new File( arg));
>
>Do I get buffered output with the first code that I don't get with the
>second code?  Or do I get the same buffered behavior with both?

You don't get buffering, or at least significant buffering. Given that
computers have at least four times as much RAM as they had when Java
io was conceived, you probably want to use 64K buffers, or read the
whole file in one fell swoop, when the file does not stay open.
see http://mindprod.com/products1.html#HUNKIO

See http://mindprod.com/applet/fileio.html
to generate you sample code for Java I/O.
-- 
Roedy Green Canadian Mind Products
http://mindprod.com
It should not be considered an error when the user starts something
already started or stops something already stopped. This applies
to browsers, services, editors... It is inexcusable to 
punish the user by requiring some elaborate sequence to atone,
e.g. open the task editor, find and kill some processes.

[toc] | [prev] | [next] | [standalone]

#8461

On 10/1/2011 8:06 AM, Roedy Green wrote:
> On Fri, 30 Sep 2011 10:00:55 -0700 (PDT), KevinSimonson
> <kvnsmnsn@hotmail.com>  wrote, quoted or indirectly quoted someone who
> said :
>
>> What's the difference between this code:
>>
>> PrintWriter destination
>>           = new PrintWriter
>>               ( new BufferedWriter( new FileWriter( new File( arg))));
>>
>> and this code:
>>
>> PrintWriter destination = new PrintWriter( new File( arg));
>>
>> Do I get buffered output with the first code that I don't get with the
>> second code?  Or do I get the same buffered behavior with both?
>
> You don't get buffering, or at least significant buffering. Given that
> computers have at least four times as much RAM as they had when Java
> io was conceived,

4??

More than 40!

>               you probably want to use 64K buffers,

64 KB buffer was not a problem when java.io was invented.

Arne

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.java.programmer

csiph-web