C# 在c中的TcpListener中未处理NullReferenceException#

我正在尝试将

TcpListener

连接到本地主机，以获得ip地址127.0.0.1和端口号8081 但我有个错误

NullReferenceException未处理
对象引用未设置为对象的实例

这是我的密码

public class Listener
{
    private TcpListener tcpListener;
    private Thread listenThread;

    Int32 port = 8081;
    IPAddress localAddr = IPAddress.Parse("127.0.0.1");
    Byte[] bytes = new Byte[256];

    public void ListenForClients()
    {
        //getting error at this line..
        this.tcpListener.Start();

        while (true)
        {
            //blocks until a client has connected to the server
            TcpClient client = this.tcpListener.AcceptTcpClient();

            //create a thread to handle communication 
            //with connected client
            Thread clientThread = new Thread(new ParameterizedThreadStart(HandleClientComm));
            clientThread.Start(client);
        }
    }

    public void HandleClientComm(object client)
    {
        TcpClient tcpClient = (TcpClient)client;
        NetworkStream clientStream = tcpClient.GetStream();

        byte[] message = new byte[4096];
        int bytesRead;

        while (true)
        {
            bytesRead = 0;

            try
            {
                //blocks until a client sends a message
                bytesRead = clientStream.Read(message, 0, 4096);
            }
            catch
            {
                //a socket error has occured
                // System.Windows.MessageBox.Show("socket");
                break;
            }

            if (bytesRead == 0)
            {
                //the client has disconnected from the server
                // System.Windows.MessageBox.Show("disc");
                break;
            }

            //message has successfully been received
            ASCIIEncoding encoder = new ASCIIEncoding();

            String textdata = encoder.GetString(message, 0, bytesRead);
            System.IO.File.AppendAllText(@"D:\ipdata.txt", textdata);



            //mainwind.setText(encoder.GetString(message, 0, bytesRead));
            //System.Windows.MessageBox.Show(encoder.GetString(message, 0, bytesRead));
            // System.Diagnostics.Debug.WriteLine(encoder.GetString(message, 0, bytesRead));
        }

        tcpClient.Close();
    }
}

我在下面的代码行得到错误

this.tcpListener.Start();

---

您的TcpListener为空。您需要对它调用new并创建它的实际实例

private TcpListener tcpListener;

应该是

private TcpListener tcpListener = new TcpListener();

---

您只声明了

tcpListener

private TcpListener tcpListener;

它没有任何价值。它是空的

在使用它之前，必须先定义它

试一试

---

您不会在任何地方创建

tcpListener

的新实例。。尝试添加类似于

tcpListener=newtcplistener（..）

创建实例时出错

private TcpListener tcpListener = new TcpListener();