JavaFX, client GUI, 2 instances causes second socket to be NULL - multithreading

Question

I've coded a client program that communicates with my arduino server. It had a swing button and a methog that ran a loop checking for any input from the server. I tried it with multiple instances running from different or/and the same IP and everything was fine. Now I tried implementing that same method for the socket in a app with JavaFX GUI. After I read here and there that it needs to be on a separate thread I did it as instructed and it seems to be working just fine. If I try to launch a second instance of it though,it imidiately throws NullPointerException on the line where i check socket.isConnected() && !Socket.isClosed(). The first instance continues to work just fine, but the other one just stays with the GUI open.
As I've done it with the same class but not on a new thread and with swing button, I can say that the problem is not on the server side.
I need to be able to launch as many instances of the program as I want while they all keep an open socket at all times. Any ideas on how to fix that ?
Update: I tryed recalling the initiation in the loop when socket is lost. It seems that the socket closes right after it is opened.
Here is the Class for the client:
package panelSouth;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;
public class Networking implements Runnable{
static Socket socket;
static OutputStreamWriter out;
public void run() {
//Initializing socket - IP/PORT
String host = "192.168.1.178";
int port = 2015;
boolean connected=true;
do{
try{
socket = new Socket(host,port);
}
catch(Exception unknownHostException){
connected=false;
System.out.println("Connecting to host...");
}
}while(connected==true);
System.out.println("Connection is a success!");
System.out.println("Requesting pin states...");
//Requesting pin states on startup.
try{
out = new OutputStreamWriter(socket.getOutputStream());
out.write("r;");
out.flush();
}catch(Exception ex){
System.out.println(ex);
}
listen();
}
//Listening for incoming commands from host
public static void listen(){
try{
BufferedReader in = new BufferedReader(
new InputStreamReader(
socket.getInputStream() ) );
while(socket.isConnected() && !socket.isClosed()){
States.commandProcess(in.readLine());
}
}catch(Exception ex){
System.out.println(ex);
}
}
//send commands.
static public void send(String command){
try{
out.write(command);
out.flush();
}catch(Exception ex){
System.out.println(ex);
}
}
//closing the socket and resetting the pins on host on close up.
static public void close(){
try{
OutputStreamWriter out = new OutputStreamWriter(socket.getOutputStream());
out.write("x;");
out.flush();
socket.close();
}catch(Exception exception){
}
}
}
And here is the Main:
public static void main(String[] args) throws Exception{
Thread network = new Thread(new Networking());
network.setDaemon(true);
network.start();
launch(args);
}

Answer 1

I removed the loops in the defining of the socket and I put recall of the function only in the catch{} part. It seems that the loop was defining more than one socket or something and when I was actually sending data to the socket, it was another socket. Also I changed the thread handling and made it with Task which seems to work a lot better with JavaFX scene.