use of bufferedwriter.newline() in server/client code

[vinit mav]

//server

import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class Main {

    public static void main(String[] args) {
        try {
            ServerSocket sc = new ServerSocket(2000);
            Socket s=sc.accept();
            OutputStream os=s.getOutputStream();
            BufferedWriter bw=new BufferedWriter(new OutputStreamWriter(os),1);
            bw.write("hi");
            bw.newLine();
            bw.flush();
        } catch (IOException ex) {}
    }

}

--------------------------------------------------------------------------------------------------------------------------------------------------------------

//client
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.Socket;
import java.net.UnknownHostException;

public class Main {
    public static void main(String[] args) 
    {
        try {
            Socket sc = new Socket("127.0.0.1", 2000);
            InputStream is=sc.getInputStream();
            BufferedReader br=new BufferedReader(new InputStreamReader(is));
            System.out.print(br.readLine());
        } catch (UnknownHostException ex) {} catch (IOException ex) {}
    }

}

--------------------------------------------------------------------------------------------------------

on the server side,if i don't write newline() ,why is nothing printed on client side even though i use flush()?

[Mike Simmons]

Well, the client is probably executing the readLine(), which means it will keep waiting until it sees something that signals the end of the line.

Incidentally it's a very bad idea to have those empty catch blocks. If something goes wrong and you do get an exception, the empty catch block will silently catch the exception, without giving you any useful information about what happened. Which makes it very difficult to detect the problem, much less fix it. I suggest replacing the catch blocks with something like:

  } catch (IOException ex) {
    ex.printStackTrace();
  } 

[Campbell Ritchie]

. . . and welcome to the Ranch

[vinit mav]

but why is it so that if i write bufferedwriter.close() instead of bufferedwriter.newline() and bufferedwriter.flush() , then the client successfully prints even though the line is not ending?
thank you very much........

[Kacper Jonczyk]

Hi Vinit,

readline() behaves like Mike have specified. It blocks until it runs into "\n", "\r", "\r\n", or EOF.
However it still keeps data already read in. It just won't be returned until function comes across one of previously specified delimiters.

You might want to check out:
readLine()
and
Source which says:

464: // We only want to return null when no characters were read before
465: // EOF.

HTH

Welcome to JavaRanch!

[vinit mav]

thanks Kacper....

[Mike Simmons]

You're welcome.

[vinit mav]

i visited a site whatismyipaddress.com and it showed my ip ,but when i put this for the ip address in this program,it didn't work.
why is this program unable to run on internet?

[Jesper de Jong]

Maybe because your computer is behind a firewall or a router which does NAT (network address translation), which causes your computer to have a different IP address in the local network than on the outside Internet.

[vinit mav]

i tried port forwarding but it still isn't working?
is there a solution for this?

[vinit mav]

does the server/client chat application only work on lan and not on internet???