C# 我希望发送按钮处于非活动状态，直到用户在文本框中键入内容。我该怎么做？

将此事件处理程序分配给文本框的事件，并将按钮的

Enabled

属性最初设置为false

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Net.Sockets;
using System.Threading;

namespace SocketClient
{

    public partial class SocketClient : Form
    {
        System.Net.Sockets.TcpClient clientSocket = new System.Net.Sockets.TcpClient();
        NetworkStream serverStream = default(NetworkStream);
        string readData = null;


        public SocketClient()
        {
            InitializeComponent();
        }


        private void getMessage()
        {
            while (true)
            {
                serverStream = clientSocket.GetStream();
                int buffSize = 0;
                byte[] inStream = new byte[10025];
                buffSize = clientSocket.ReceiveBufferSize;
                serverStream.Read(inStream, 0, buffSize);
                string returndata = System.Text.Encoding.ASCII.GetString(inStream);
                readData = "" + returndata;
                msg();
            }
        }


        private void msg()
        {
            if (this.InvokeRequired)
                this.Invoke(new MethodInvoker(msg));
            else
                textDisplay.Text = textDisplay.Text + Environment.NewLine + " >> " + readData;
        }


        private void buttonConnect_Click(object sender, EventArgs e)
        {
            readData = "Conected to NYP Chat Server ...";
            msg();
            clientSocket.Connect("127.0.0.1", 8888);
            serverStream = clientSocket.GetStream();

            byte[] outStream = System.Text.Encoding.ASCII.GetBytes(textName.Text + "$");
            serverStream.Write(outStream, 0, outStream.Length);
            serverStream.Flush();

            Thread ctThread = new Thread(getMessage);
            ctThread.Start();
        }


        private void buttonSend_Click(object sender, EventArgs e)
        {
            // send text
            byte[] outStream = System.Text.Encoding.ASCII.GetBytes(textSend.Text + "$");
            serverStream.Write(outStream, 0, outStream.Length);
            serverStream.Flush();
            //clear textsend textbox
            textSend.Text = "";

        }

        private void textDisplay_TextChanged(object sender, EventArgs e)
        {
            textDisplay.SelectionStart = textDisplay.Text.Length;
            textDisplay.ScrollToCaret();
            textDisplay.Refresh();
        }
    }
}

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兄弟再次感谢，另一个问题是，如果我没有连接到我的服务器，并在发送文本中键入一些文本n按send，我的程序中将显示一条警告“serverStream.Write（outStream，0，outStream.Length）；”插入一个检查

serverStream

是否为空引用。如何做，对不起，如果（serverStream==null）{…}否则{…}在何处插入检查？

private void textSend_TextChanged(object sender, EventArgs e)
{
    buttonSend.Enabled = !string.IsNullOrEmpty(textSend.Text);
}