Thread: problem using Sockets

Hi coders!
Im new to Network programming and m currently exploring java.net ...... i am building a simple client server comm.. for that my code for server is:

 
 
 
import java.net.*;
import java.io.*;
public class Socket {
public static void main(String args[]) throws IOException {
// Register service on port 1254
ServerSocket s = new ServerSocket(1254);
java.net.Socket s1=s.accept(); // Wait and accept a connection
// Get a communication stream associated with the socket
OutputStream s1out = s1.getOutputStream();
DataOutputStream dos = new DataOutputStream (s1out);
// Send a string!
dos.writeUTF("Hi there");
// Close the connection, but not the server socket
dos.close();
s1out.close();
s1.close();
 
 
 
 
 
 
	}
 
public InputStream getInputStream() {
	// TODO Auto-generated method stub
	return null;
}
 
}

and for client is:

 
 
 
 
 
 
 
import java.net.*;
import java.io.*;
public class Client {
 
	public static void main(String[] args) {
		// Open your connection to a server, at port 1254
		Socket s1 = new Socket("localhost",1254);
		// Get an input file handle from the socket and read the input
		InputStream s1In = s1.getInputStream();
		DataInputStream dis = new DataInputStream(s1In);
		String st = new String (dis.readUTF());
		System.out.println(st);
		// When done, just close the connection and exit
		dis.close();
		s1In.close();
		s1.close();
 
 
 
	}
 
}

the error returned is:



Exception in thread "main" java.net.BindException: Address already in use: JVM_Bind
at java.net.DualStackPlainSocketImpl.bind0(Native Method)
at java.net.DualStackPlainSocketImpl.socketBind(Unkno wn Source)
at java.net.AbstractPlainSocketImpl.bind(Unknown Source)
at java.net.PlainSocketImpl.bind(Unknown Source)
at java.net.ServerSocket.bind(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at Socket.main(Socket.java:9)

i need to know that y this so...moreover how should i manage to run both programs on same machine to get client-server comm....
Any help will be appreciated.
thanks in advance

Originally Posted by Jedi khan

Exception in thread "main" java.net.BindException: Address already in use: JVM_Bind

Try using a different port number. Make sure to close the server thread before starting a new one, as it is possible an old instance of the project is holding the port open in the background.

Also tell me please how to run both programs(Server,Client) on one and the same machine.

Install both on the machine.
Launch them both. Probably the server first.
Exactly what are you stuck on? The ip? Use localhost.
Well I could keep guessing...
Please ask a more specific question and try to explain what you have tried and where you are stuck

Originally Posted by jps

Install both on the machine.
Launch them both. Probably the server first.
Exactly what are you stuck on? The ip? Use localhost.
Well I could keep guessing...
Please ask a more specific question and try to explain what you have tried and where you are stuck

Well if you don't mind plz tell me what u mean by install....i m not getting ...did u mean to run them separately or what i should take ???

Can you also change your server code class name to Server. Don't take Socket because we alread have Socket class in jdk.

Syed.

I will but its not the solution Syed Sahab..

Originally Posted by Jedi khan

Well if you don't mind plz tell me what u mean by install....i m not getting ...did u mean to run them separately or what i should take ???

Here "Install" simply means make the jar(s) available to the machine you wish to execute them on.
I'm not going to give a step by step process that covers every possible scenario. Explain what you are doing and what problem you have, specifically. If there is an error message, copy paste the full text to the forum

Originally Posted by jps

Here "Install" simply means make the jar(s) available to the machine you wish to execute them on.
I'm not going to give a step by step process that covers every possible scenario. Explain what you are doing and what problem you have, specifically. If there is an error message, copy paste the full text to the forum

I am intending to run both programs on the same machine
The error i am encountering on every run of the client program is
Exception in thread "main" java.net.BindException: Address already in use: JVM_Bind
at java.net.DualStackPlainSocketImpl.bind0(Native Method)
at java.net.DualStackPlainSocketImpl.socketBind(Unkno wn Source)
at java.net.AbstractPlainSocketImpl.bind(Unknown Source)
at java.net.PlainSocketImpl.bind(Unknown Source)
at java.net.ServerSocket.bind(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at Socket.main(Socket.java:9)

works fine for me...you also might want to do s.close(); in the server to close the server socket too and in the client you might want to use a try catch or throws or something

you sure you dont have something already using port 1254? if you are on windows try running a command prompt and doing netstat -a
see if your port is there being used


edit: now i ran into the problem you are having...as jps said its because you still have an instance of it running using that port

Originally Posted by derekxec

works fine for me...you also might want to do s.close(); in the server to close the server socket too and in the client you might want to use a try catch or throws or something

you sure you dont have something already using port 1254? if you are on windows try running a command prompt and doing netstat -a
see if your port is there being used


edit: now i ran into the problem you are having...as jps said its because you still have an instance of it running using that port

But when i ran the client part it returned an error pointint to:

 
String st = new String (dis.readUTF());

also returning NullPointerException
For running Server part it returns:
Exception in thread "main" java.net.BindException: Address already in use: JVM_Bind
at java.net.DualStackPlainSocketImpl.bind0(Native Method)
at java.net.DualStackPlainSocketImpl.socketBind(Unkno wn Source)
at java.net.AbstractPlainSocketImpl.bind(Unknown Source)
at java.net.PlainSocketImpl.bind(Unknown Source)
at java.net.ServerSocket.bind(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at Socket.main(Socket.java:13)

ServerSocket s = new ServerSocket(1254);

Its driving me mad now as i am too slow now cz of this bug!!!

What happened when you tried a different port number as suggested in post #2?
I did not look at or run the code, but looking at post #10 it would seem derekxec may have, and suggested the same thing.
No one is going to hand over working code, if you need more help, try what was suggested and report the results if you still need help.

yeah i ran the code and only could get that bindexception if i tried running it again with 1 instance of it already running...because of course the first instance was listening on the port already

That would verify what you were told in post #2 and 10.
Please mark the thread as solved if you have no further questions