Server & Client are both waiting

[S Reddy]

Hi.... I am trying to write a program which contains a server & a client. First I write the program as server sends some messages and client prints them. It is working fine. But when I added the code to send messages from client to server... Now it is not working. My code is
Chat Server

  import java.io.*;
import java.net.*;
 
import java.util.*;
 
public class ChatServer {
 
        public static void main(String[] args) throws IOException {
                ServerSocket ssck= new ServerSocket(28000);
 
                while(true){
                        Socket sck= ssck.accept();
 
System.out.println("Accepted a client");
 
                        PrintWriter pw= new PrintWriter(sck.getOutputStream());
BufferedReader bfr= new BufferedReader(new InputStreamReader(sck.getInputStream()));
 
                        Random r= new Random(10);
int i= java.lang.Math.abs(r.nextInt()%15);
System.out.println("Random number "+i);
 
System.out.println("Just about to read from Client...........");
System.out.println("Client:  "+ bfr.readLine().toString());
 
while(i-- != 0) 
pw.println("Value:"+i);
                        pw.write("bye");
 
                        pw.close();
bfr.close();
                        sck.close();
                }
        }
}
  

Chat Client

 import java.io.*;
import java.net.*;
 
public class ChatClient {
 
        public static void main(String[] args) throws Exception {
 
                Socket sck= new Socket("127.0.0.1", 28000);
 
                BufferedReader bfr= new BufferedReader(new InputStreamReader(sck.getInputStream()));
PrintWriter pw= new PrintWriter(sck.getOutputStream());
System.out.println("Got a writer to the server");
pw.println("hi..from client");
 
                Thread t= new Thread(new ccthrd(bfr));
                t.start();
 

t.join();
pw.close();
bfr.close();
sck.close();
        }
}
 
class ccthrd implements Runnable {
 
        BufferedReader bfr1;
        String str;
 
        ccthrd(BufferedReader b) {
                this.bfr1=b;
        }
 
        public void run() {
 

                do {
               
try {
str= bfr1.readLine();
                        } catch(IOException e) {}
 
                        if(str==null)
                        System.exit(0);
                        
System.out.println(str);
 
                } while( !str.equals("bye"));
 

        }
}   

It seems that server is waiting at this line
System.out.println("Client: "+ bfr.readLine().toString());

If I commented out this line, the program is working fine. I am unable to understand what I have done wrong. As I was new to Java, please give me some suggestion.

[Martijn Verburg]

I'd say that if you're writing socket based code you're a little beyond 'beginner' level! You've basically been caught out by a little gotcha.

It's always 'good practice' to flush your PrintWriter after you've built up what you want to send (this is true for any socket level communication).

I think you'll find that a

pw.flush()

after

pw.println("hi..from client");

will do the trick.

Cheers,
Martijn

[S Reddy]

Thank you very much Martijn Verburg. It is working now.