multithreading - Need help getting my basic socket-server working -

so, managed basic single-connection server running, i'm trying convert multi-threaded server small multilayer project wanted do, i'm self-taught , stumble on things, , networking main 1 i've been trying understand long while now, possibly guys can help..

problem: when had 1 thread writeutf , readutf worked fine, sent utf , closed connections, although i've moved multi-thread i'm not sure if it's client not sending utf, server not receiving utf, or server not re-sending utf, perhaps guys let me know, here's code.

server sided code

server.java

package testserver.net; /**  * server class, server main class  * instantiating related server-side functionality,  * server listens incoming connections aswell handles  * data transmitted between two.  *   *   * @author christian  */ import java.io.*; import java.net.*; import java.sql.*;  import testserver.net.players.player;   public class server {     player[] player = new player[config.max_connections];     serversocket serversocket;     socket socket;     dataoutputstream out;     datainputstream in;  public server() throws ioexception {     // open server on following port     system.out.println("attempting setup server...");     serversocket = new serversocket(43594);     system.out.println("server officially setup on port: 43594");     // tell server accept connections     while (true) {         socket = serversocket.accept();         for(int = 0; < config.max_connections; i++) {             system.out.println("server waiting connections...");             system.out.println("connection from: " +socket.getinetaddress());             // setup server send out data.             out = new dataoutputstream(socket.getoutputstream());             in = new datainputstream(socket.getinputstream());             if(player[i] == null) {                 player[i] = new player(out, in, player);                 thread thread = new thread();                 thread.start();                 break; // end loop start listening more connections             }         }     } }  public static void main(string args[]) throws ioexception {     new server(); } } 

player.java

package testserver.net.players;  import testserver.net.*; import java.io.*;  public class player implements runnable { player[] player = new player[config.max_connections]; dataoutputstream out; datainputstream in;   public player(dataoutputstream out, datainputstream in, player[] player) {     this.in = in;     this.out = out;     this.player = player; }  public void run() {     while(true) {         try {             string message = in.readutf();             for(int = 0; < config.max_connections; i++) {                 if(player[i] != null) {                     player[i].out.writeutf(message);                 }             }         } catch (ioexception e) {             // todo auto-generated catch block             e.printstacktrace();         }      } } } 

client sided code

client.java

package testclient.net; import java.net.*; import java.util.scanner; import java.io.*;  import testclient.net.util.input;  public class client {  socket socket; datainputstream in; dataoutputstream out;  public client() throws unknownhostexception, ioexception {     // set client connect (ip, port);     system.out.println("attempting connect server on port: 43594");     socket = new socket("localhost", 43594);     system.out.println("successfully connected server...");     in = new datainputstream(socket.getinputstream());     out = new dataoutputstream(socket.getoutputstream());     input input = new input(in);     thread thread = new thread(input);     thread.start();     scanner scanner = new scanner(system.in);     while(true)  {         string sendmessage = scanner.nextline();         out.writeutf(sendmessage);      } }  public static void main(string args[]) throws unknownhostexception, ioexception {     new client(); } } 

input.java

    package testclient.net.util;   import java.io.datainputstream; import java.io.ioexception;  public class input implements runnable {      datainputstream in;      public input(datainputstream in) {         this.in = in;     }      public void run() {         while (true) {             string message;             try {                 message = in.readutf();                 system.out.println(message);             } catch (ioexception e) {                 // todo auto-generated catch block                 e.printstacktrace();             }          }     } } 

you create , start thread object in server, failed pass player runnable it.