SocketException was unhandled

after i am connected to the server, i click on the connect button again i get SocketException was unhandled on clientSocket.Connect("127.0.0.1", 8888); How to solve this?

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 = "开发者_StackOverflow社区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)
    {
       // Show msg box if no server is connected
        if (serverStream == null)
        {
            MessageBox.Show("Please connect to a server first!");
            return;
        }

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

        // Clear text
        textSend.Text = "";


    }

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

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

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You can't connect clientSocket more than once. What do you expect to happen when you click the button the second time?

You could check the state of the socket and if it's connected then don't attempt another connection. Or put some exception handling in.