Error by submitting objects with socket

Question

Hallo,
I allways get the following error massage:
Error:
java.net.ConnectException: Connection timed out: connect
Exception in thread "Thread-0" java.lang.NullPointerException
at com.Receiver.read(Receiver.java:36)
at Input.write(Kommunicator.java:111)
at Input.run(Kommunicator.java:137)
Error:
java.net.ConnectException: Connection timed out: connect
Here is my code:
import com.*;
import TerminalIO.*;
import java.util.*;
import java.io.*;
import java.net.*;
public class Kommunicator
     public static void main(String [] args){
          KeyboardReader inread = new KeyboardReader();
          int port = inread.readInt();
          String ip =inread.readLine();
          Emitter out = new Emitter(ip, port);
          Input in= new Input(new Receiver(ip, port));
          try{
               in.start();
               boolean flag=true;
               while(flag){
                    out.open();
                    if(line.equalsIgnoreCase("\\quit")){
                         out.write("User left");
                         in.interrupt();
                         flag=false;
                    else{
                         out.write(line);
                    out.close();
          catch(IOException e){
               System.out.println("Error:\n"+e.toString());
class Input extends Thread
     private Receiver out;
     public Input(Receiver a){out=a;}
     private void open(){
          try{
               out.open();
               super.start();
          catch(IOException e)
               System.out.println("Error:\n"+e.toString());
     private void close(){
          try{
               out.close();
          catch(IOException e)
               System.out.println("Error:\n"+e.toString());
     private void write(){
          try{
               Object temp=out.read();
               if(!temp.equals(null))
                    String line=temp.toString();
                    do
                    System.out.println("Other:"+line);
                    line=out.read().toString();
                    }while(!line.equals(""));
          catch(IOException e)
               System.out.println("Error:\n"+e.toString());
          catch(ClassNotFoundException e)
               System.out.println("Error:\n"+e.toString());
     public void run()
          open();
          write();
          close();
package com;
import java.net.*;
import java.io.*;
public class Receiver
     private String ip;
     private int port;
     private ObjectInputStream ois;
     private Socket sock;
     public Receiver(String a, int b)
          ip=a;
          port=b;
     public void open() throws IOException
          sock = new Socket(InetAddress.getByName(ip), port);
          ois = new ObjectInputStream(sock.getInputStream());
          sock.setSoTimeout(3000);
     public void close() throws IOException
          ois.close();
          sock.close();
     public Object read() throws IOException,ClassNotFoundException
          Object temp=null;
          temp=ois.readObject();
          return temp;
     public int getPort()
     {return port;}
     public String getIp()
     {return ip;}
package com;
import java.io.*;
import java.net.*;
public class Emitter
     private String ip;
     private int port;
     private Socket sock;
     private ObjectOutputStream oos;
     public Emitter(String a, int b)
          ip=a;
          port=b;
     public String getIp()
     {return ip;}
     public int getPort()
     {return port;}
     public void open() throws IOException
          sock = new Socket(InetAddress.getByName(ip),port);
          oos =new ObjectOutputStream(sock.getOutputStream());
          sock.setSoTimeout(3000);
     public void write(Object a) throws IOException
     {oos.writeObject(a);}
     public void close() throws IOException
          oos.close();
          sock.close();
}I hope you can help me with my problem and I hope you can answer my questions;
1) is it a general problem with socket, that it is not allowed to submit objects on a permanent way?
2) is it there another way how to submit object?
3) can the problem be caused through trying to submit packeges in a lan?

Answer 1

1. When you get an exception trying to construct any object, it is poor practice to print and ignore it.
2. It is invalid to continue as though the object had been constructed.
3. In this case you failed to connect but then continued to the read method using a null socket reference.
4. You need to restructure your code so that it reacts correctly to exceptions.
5. Then you need to solve the question of why the connect failed.