manage socket connection in Java over tcp

Question

I wrote a client which basically just open a socket and send content over the connection. ( the content follows the Http protocol)

The problem I'm facing regards to the question - how and when should i close the connection. The issue is that the connection sometime closes too early ("FIN" is sent to the server before the server answered).

in this case the server's answer is lost.
I tried to use Thread.sleep before closing the connection but nothing seems to affect the time between the content is sent and the "FIN" message is sent. (viewed in Wireshark)

The answer sometimes arrive and sometimes not ( race condition).

How can i delay the "FIN" message so i won't miss the server's response?

i added the relevant class. The relevant function is sendContentOverSocket

public class SocketClient {

           private String hostName;
           private int portNumber;
           private Socket ConnectionSocket;

           public void init(String hostName, int portNumber){
                          this.hostName = hostName;
                          this.portNumber = portNumber;
                          this.ConnectionSocket=createSocketConnection();

           }

           private Socket createSocketConnection() {
                          Socket socket = null;
                          try {
                                         socket = new Socket(this.hostName, this.portNumber);
                                         return socket;
                          } catch (UnknownHostException e) {
                                         e.printStackTrace();
                          } catch (IOException e) {
                                         e.printStackTrace();
                          }

                          return socket;
           }

           public void sendContentOverSocket(String content) {
                          try {
                                         PrintWriter out = new PrintWriter(
                                                                       ConnectionSocket.getOutputStream(), true);
                                         BufferedReader in = new BufferedReader(new InputStreamReader(
                                                                       ConnectionSocket.getInputStream()));
                                         out.print(content);

                                         try {
                                                        Thread.sleep(2000);
                                         } catch (InterruptedException e) {
                                                        // TODO Auto-generated catch block
                                                        e.printStackTrace();
                                         }

                                         out.close();
                                         in.close();                           
                                         ConnectionSocket.close();

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

}

Answer 1

solved.

i now understand how it works. what i was missing in the client is the attempt to read from the input Stream. When you try to read

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

the client waits for input. The only thing that will break this loop is the server closing the connection.

after that happens you can safely close the connection on the client side. No need to delay the FIN and such...