Java tcp server programming does not work

Question

I use this code to run simple TCP Server by JAVA and I use Socket Protocol android application to be client. The problem is when the client connected then I send the message the Server side do nothing until I disconnected the client the massage appear after that. I think something stuck at while((inputLine = in.readLine()) != null)

import java.net.*;
import java.io.*;

public class TCPIP {

public static void main(String[] args) throws IOException {
    ServerSocket serverSocket = null;
    try{
        serverSocket = new ServerSocket(10007);
    }
    catch(IOException e)
    {
        System.err.println("Could not listen on port 10007");
        //System.exit(1);
    }
    Socket clientSocket = null;
    System.out.println("Waiting for connection....");

    try{
        clientSocket = serverSocket.accept();
    }
    catch(IOException e){
        System.err.println("Accept Failed");
        //System.exit(1);
    }
    System.out.println("Connection Successful");
    System.out.println("Waiting for input");

    PrintWriter out = new PrintWriter(clientSocket.getOutputStream(),true); 
    BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));


    String inputLine;


    while((inputLine = in.readLine()) != null) 
    {
        System.out.println("Server: "+ inputLine);
        out.println(inputLine);

        if(inputLine.equals("Bye."))
        {
            break;
        }
    }
    out.close(); 
    in.close(); 
    clientSocket.close(); 
    serverSocket.close(); 
}

}

Yes it is. Because I test this android app(my client) with c# socket before. — Sarin Suriyakoon
– Sarin Suriyakoon, Commented Dec 30, 2014 at 13:37
It needs to be more specific: a line ends with a newline. Probably the client is not sending a newline and so the readLine() method is still waiting for it. — Gimby
– Gimby, Commented Dec 30, 2014 at 13:42

specializt · Accepted Answer · 2014-12-30 14:05:51Z

1

while((inputLine = in.readLine()) != null)

is bad code, you should use

inputLine = in.readLine();
while(inputLine != null)
{
   inputLine = in.readLine();
}

instead. readLine() waits for the newline-character - make sure your server sends it or else your client will block until the connection is closed : https://docs.oracle.com/javase/6/docs/api/java/io/BufferedReader.html#readLine()

Reads a line of text. A line is considered to be terminated by any one of a line feed ('\n'), a carriage return ('\r'), or a carriage return followed immediately by a linefeed.

edited Dec 30, 2014 at 14:05

answered Dec 30, 2014 at 13:45

specializt

1,91016 silver badges26 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Java tcp server programming does not work

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related