Why using BefferedReder and PrintWriter if we have Input/OutputStream

Question

hi
i've been wondering if we have an InputStream and OutputStream why using PrintWriter and BufferedReader
                in=s.getInputStream();
                out=s.getOutputStream();
                bfr=new BufferedReader(new InputStreamReader(in));
                writer=new PrintWriter(out,true);where s ia a socket
Edited by: scrolldown on Mar 29, 2008 3:03 AM
Edited by: scrolldown on Mar 29, 2008 3:04 AM

Answer 1

Everything that is a InputStream/OutputStream is used to handle raw byte streams.
Everything that is a Reader/Writer is used to handle character data.
In your case the InputStreamReader provides the conversion from raw bytes to character data. Usually it does so using some specified encoding, in your case it uses your platform default encoding.
The PrintWriter does the same for the output, but doesn't allow you to specify an encoding (for this you'd have to use an OutputStreamWriter).
And please note, that it's usually an error to do any byte -> character or character -> byte conversion without specifying a character set, especially when handling sockets, because then the platform default encoding will be used which can be different from computer to computer and thus you don't know what exactly is sent over the wire.
If you don't know what I'm talking about, then read [The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)|http://www.joelonsoftware.com/articles/Unicode.html], an excellent article that gives a good overview over the matter.