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I am getting the warning:

Non-nullable field 'tcpListener' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.

Here is my code:

using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.Net.Sockets;

namespace GameServer
{
    class Server
    {
        public static int MaxPlayers { get; private set; }
        public static int Port { get; private set; }
        public static Dictionary<int, Client> clients = new Dictionary<int, Client>();
        private static TcpListener tcpListener;

        public static void Start(int _maxPlayers, int _port)
        {
            MaxPlayers = _maxPlayers;
            Port = _port;

            Console.WriteLine("Starting server...");
            InitializeServerData();

            tcpListener = new TcpListener(IPAddress.Any, Port);
            tcpListener.Start();
            tcpListener.BeginAcceptTcpClient(new AsyncCallback(TCPConnectCallback), null);

            Console.WriteLine($"Server started on {Port}");
        }

        private static void TCPConnectCallback(IAsyncResult _result)
        {
            TcpClient _client = tcpListener.EndAcceptTcpClient(_result);
            tcpListener.BeginAcceptTcpClient(new AsyncCallback(TCPConnectCallback), null);
            Console.WriteLine($"Incoming connection from {_client.Client.RemoteEndPoint}...");

            for (int i = 0; i <= MaxPlayers; i++)
            {
                if (clients[i].tcp.socket == null)
                {
                    clients[i].tcp.Connect(_client);
                    return;
                }
            }

            Console.WriteLine($"{_client.Client.RemoteEndPoint} failed to connect: Server full!");
        }

        private static void InitializeServerData()
        {
            for (int i = 0; i <= MaxPlayers; i++)
            {
                clients.Add(i, new Client(i));
            }
        }
    }
}

If I change it to a nullable type, I get this warning:

Dereference of a possibly null reference.

If anyone has a fix to this, I would be very grateful.

randomdudeontheinternet
  • 1
  • Does this answer your question? [Non-nullable property must contain a non-null value when exiting constructor. Consider declaring the property as nullable](https://stackoverflow.com/questions/67505347/non-nullable-property-must-contain-a-non-null-value-when-exiting-constructor-co) – Charlieface Jan 24 '22 at 19:05
  • You don't have a constructor. Perhaps you should create a constructor and create your `TCPListener` instance there. – Tim Roberts Jan 24 '22 at 19:06
  • Try ```private static TcpListener? tcpListener = null;``` The lack of ```public``` on the **server** class is interesting, not sure how that works. It kind of looks like a singleton pattern. – Phil Huhn Apr 30 '22 at 13:56

0 Answers0