java - Singleton networking object gives error on second call -

communication class of singleton object created:

import java.net.*; import java.io.*; import java.util.scanner;  public class communication {      private static communication minstance = null;      private static final string request_login = "login";          private bufferedoutputstream socketoutput = null;     private printwriter printout = null;     private socket socket = null;     private scanner reader = null;        private communication()     {         //connect server using loopback address         try{             socket = new socket("127.0.0.1", 4242);             //set inputs , out puts             socketoutput = new bufferedoutputstream(socket.getoutputstream());             printout = new printwriter(socket.getoutputstream(), true);             reader = new scanner(socket.getinputstream());         }         catch( unknownhostexception uhe){             uhe.printstacktrace();         }         catch( ioexception ex){             ex.printstacktrace();         }     }     public static communication getinstance(){         if(minstance == null)         {             minstance = new communication();         }         return minstance;     }         //sample method requesting login     public boolean login(string u, string p){                try{                         string username = u;             string password = p;                              printout.printf("%s!%s@%s\n", request_login, username, password);             int loginstatus = reader.nextint();             if (loginstatus == 1){                     socketoutput.close();                     socket.close();                                      return true;}             else{                 socketoutput.close();                 socket.close();                              return false;             }                    }         catch( ioexception ex){             ex.printstacktrace();             return false;         }     }    } 

another class using singleton object repeatedly:

public class go{     public static void main(string[] args) {                     communication.getinstance().login("user", "password");         communication.getinstance().login("user", "password");     } } 

first call alright , authentication happens. second call invokes error:

exception in thread "main" java.util.nosuchelementexception     @ java.util.scanner.throwfor(scanner.java:907)     @ java.util.scanner.next(scanner.java:1530)     @ java.util.scanner.nextint(scanner.java:2160)     @ java.util.scanner.nextint(scanner.java:2119)     @ communication.login(communication.java:49)     @ go.main(go.java:7) 

how can use object repeatedly ?

the login method closes socket, on second call scanner works on dead input stream. in application flow broken.

the communicator singleton, , break because invalidate it's assets in login method. getinstance() method finds singleton still set (because not set singleton null @ end of login) , returns dead object.

then scanner tries readint on closed socket's input stream. suppose not supposed work.