a question about PrintWirter.

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2 total messages Started by Zhilei Ma Tue, 26 Nov 2002 16:55

#730

Author: Zhilei Ma
Date: Tue, 26 Nov 2002 16:55

30 lines
1694 bytes

Hello all,

i habe wrote a code piece like the following:

import java.io.*;

public class PrintWriterDemo
{
    public static void main(String[] args) throws IOException
    {
 PrintWriter pw = new PrintWriter(System.out, false);
 pw.println("this is a String.");

 int i=-7;
 pw.println(i);

 double d = 2.4e-7;
 pw.println(d);
    }
}

when i run this programm, it output nothing, until i changed the parameter
of the constructor of PrintWriter from "false" to "true". I know that the
boolean paremeter means that "autoFlush - A boolean; if true, the println()
methods will flush the output buffer". But i cann't good understand it. Can
anyone explain it to me?

Thanks a lot!

Zhilei

Re: a question about PrintWirter.

#734

Author: John
Date: Thu, 28 Nov 2002 16:02

41 lines
2158 bytes

The PrintWriter is buffered.  It will only flush itself when println()
is called and autoFlush is turned on (true).  There is a method called
flush() in which you can do the flushing yourself.

John


On Tue, 26 Nov 2002 17:55:49 +0100, "Zhilei Ma" <zhilei.ma@iao.fhg.de>
wrote:

>Hello all,
>
>i habe wrote a code piece like the following:
>
>import java.io.*;
>
>public class PrintWriterDemo
>{
>    public static void main(String[] args) throws IOException
>    {
> PrintWriter pw = new PrintWriter(System.out, false);
> pw.println("this is a String.");
>
> int i=-7;
> pw.println(i);
>
> double d = 2.4e-7;
> pw.println(d);
>    }
>}
>
>when i run this programm, it output nothing, until i changed the parameter
>of the constructor of PrintWriter from "false" to "true". I know that the
>boolean paremeter means that "autoFlush - A boolean; if true, the println()
>methods will flush the output buffer". But i cann't good understand it. Can
>anyone explain it to me?
>
>Thanks a lot!
>
>Zhilei
>

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