Java socket connection

Question

I've tried to test socket connection in Java, but failed. Here is my code (two simple applications, server and client):

public class TestServer {

public static void main(String args[]) throws IOException {
    ServerSocket serverSocket = new ServerSocket(1111);
    System.out.println("Server socket created");
    Socket socket = serverSocket.accept();
    System.out.println("Socket accepted");
    PrintWriter output =  new PrintWriter(socket.getOutputStream(), true);
    System.out.println("Output created");
    output.write("Output string");
    socket.close();
    serverSocket.close();       
}
}

public class TestClient {

public static void main(String args[]) throws IOException {

    Socket socket = new Socket("127.0.0.1", 1111);
    BufferedReader input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
    System.out.println("Input: " + input.readLine());
    socket.close();

}

}

Output is (after running a server and, after it, client):

Server socket created
Socket accepted
Output created
Input: null

I've no idea what's the problem and why client didn't receive string sent to it. I'd appreciate any help.

Felipe · Accepted Answer · 2011-12-16 12:18:17Z

6

Usually when I use classes like PrintWriter or OutputStream I need to flush its contents to send the data through a socket or write it to a file.

answered Dec 16, 2011 at 12:18

Felipe

7,54113 gold badges59 silver badges76 bronze badges

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

1 Comment

Yury Pogrebnyak Over a year ago

That's exactly what my problem was. Thanks.

Tudor · Accepted Answer · 2011-12-16 12:18:51Z

2

input.readLine expects a newline in the input string. Try to replace the output.write with output.println.

I just tested it now and it should work correctly like this.

edited Dec 16, 2011 at 12:18

answered Dec 16, 2011 at 12:12

Tudor

62.6k13 gold badges105 silver badges148 bronze badges

1 Comment

Tudor Over a year ago

@Peter Lawrey: yeah, sorry, I was in a rush. Should work now.

user207421 · Accepted Answer · 2011-12-17 07:16:40Z

2

In addition to all the other comments, you shouldn't close the socket itself, you should close the outermost output stream you have created around the socket's output stream. That will:

(a) flush the output stream (b) close it (c) close the input stream, and (d) close the socket.

answered Dec 17, 2011 at 7:16

user207421

312k45 gold badges324 silver badges493 bronze badges

Comments

Tudor · Accepted Answer · 2011-12-16 12:21:00Z

1

//Put the line 

output.flush();

//in the end of the TestServer.java

//and in the TestClient.java I have used the code as given below

Socket socket = new Socket("127.0.0.1", 1111);
    BufferedReader input = new BufferedReader(new InputStreamReader(socket.getInputStream()));
    String str;
    while((str=input.readLine())!=null){
        System.out.println("Input: " + str);
    }
    socket.close();

}

edited Dec 16, 2011 at 12:21

Tudor

62.6k13 gold badges105 silver badges148 bronze badges

answered Dec 16, 2011 at 12:19

Ramakanth77

994 bronze badges

Collectives™ on Stack Overflow

Java socket connection

4 Answers 4

1 Comment

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related