server and client in java -

i have problem client-server. when run server, after client, server write client connected server can write nothing in console. can check problem? because i'm new in java. try scanner doesn't work too.

server:

package ts_server;  import java.io.bufferedreader;   import java.io.ioexception;   import java.io.inputstreamreader;   import java.io.printwriter;   import java.net.serversocket;   import java.net.socket;    public class server   {       private static final int port = 50000;       static boolean flaga = true;        private static serversocket serversocket;       private static socket clientsocket;        public static void main(string[] args) throws ioexception       {           serversocket = null;           try           {               serversocket = new serversocket(port);           }           catch(ioexception e)           {               system.err.println("could not listen on port: "+port);               system.exit(1);           }            system.out.print("waiting connection...");            thread t = new thread(new runnable()           {               public void run()               {                   try                   {                       while(flaga)                       {                           system.out.print(".");                           thread.sleep(1000);                       }                   }                   catch(interruptedexception ie)                   {                       //                   }                    system.out.println("\nclient connected on port "+port);               }           });           t.start();            clientsocket = null;           try           {               clientsocket = serversocket.accept();               flaga = false;           }           catch(ioexception e)           {               system.err.println("accept failed.");               t.interrupt();               system.exit(1);           }            final printwriter out = new printwriter(clientsocket.getoutputstream(),true);           final bufferedreader in = new bufferedreader(new inputstreamreader(clientsocket.getinputstream()));            t = new thread(new runnable()           {               public void run()               {                   try                   {                       thread.sleep(5000);                        while(true)                       {                           out.println("ping");                           system.out.println(system.currenttimemillis()+" ping sent");                            string input = in.readline();                            if(input.equals("pong"))                           {                               system.out.println(system.currenttimemillis()+" pong received");                           }                           else                           {                               system.out.println(system.currenttimemillis()+" wrong answer");                                out.close();                               in.close();                               clientsocket.close();                               serversocket.close();                               break;                           }                             thread.sleep(5000);                       }                   }                   catch(exception e)                   {                       system.err.println(system.currenttimemillis()+" unexpected error");                   }               }           });           t.start();       }   }  

client:

package ts_client;  import java.io.bufferedreader; import java.io.ioexception; import java.io.inputstreamreader; import java.io.printwriter; import java.net.socket;  public class client {     private static final int port = 50000;     private static final string host = "localhost";      public static void main(string[] args) throws ioexception     {         socket socket = null;          try         {             socket = new socket(host, port);         }         catch(exception e)         {             system.err.println("could not connect "+host+":"+port);             system.exit(1);         }          final printwriter out = new printwriter(socket.getoutputstream(),true);         final bufferedreader in = new bufferedreader(new inputstreamreader(socket.getinputstream()));          thread t = new thread(new runnable()         {             public void run()             {                 long start = system.currenttimemillis();                  while (true)                 {                     try                     {                         string input = in.readline();                          if (input != null)                         {                             system.out.println(system.currenttimemillis() + " server: " + input);                         }                          if (input.equals("ping"))                         {                             if(system.currenttimemillis()-start>30000)                             {                                 out.println("pon g");                                 system.out.println(system.currenttimemillis() + " client: pon g");                                 break;                             }                              out.println("pong");                             system.out.println(system.currenttimemillis() + " client: pong");                         }                     }                     catch (ioexception ioe)                     {                         //                     }                 }             }         });         t.start();          out.close();         in.close();         socket.close();     } } 

don't close streams , socket until client running.

out.close(); in.close(); socket.close();