Visual Studio C＃标签更新循环

Question

I am hoping someone can help me, I have a loop which generates a label for each instance, this also includes an if statement which changes the colour of the label. However, when the loop begins again the labels are there but they don't change any colour within the if statement. I will paste my code below; I am hoping someone can help me fix my issue in changing the colour of the label

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

namespace VIACamMonitoring
{
    public partial class Form1 : Form
    {          
        private static Form1 instancef;

        string tempString = "";
        List<string> quick = new List<string>();
        List<TextBox> list = new List<TextBox>();

        string[] cat2;
        string[] cat;

        int location = 99;
        int location2 = 102;

        int hello = new int();   

        public Form1()
        {
            InitializeComponent();
            instancef = this;
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            System.Timers.Timer timer = new System.Timers.Timer();
            timer.Interval = 300000; //1800000;
            timer.Elapsed += timer_Elapsed;
            timer.Start();

        }  

        static void timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
        {
            string[] cat2;
            string[] cat;
            List<string> quick = new List<string>();
            List<TextBox> list = new List<TextBox>();
            List<Label> labellist = new List<Label>();
            int location = 99;
            int location2 = 102;
            byte[] buffer = new byte[300];  

            StreamReader textread = new StreamReader("config.txt");
            string AllData = textread.ReadToEnd();
            string[] ssize = AllData.Split(new string[] { "\n" }, StringSplitOptions.RemoveEmptyEntries);

            foreach (string line in ssize)
            {    
                cat2 = line.Split(new string[] { "," }, StringSplitOptions.RemoveEmptyEntries);
                string instance = cat2[0];
                string instance2 = cat2[1];
                string instance3 = cat2[2];
                string instance4 = cat2[3];
                string instance5 = cat2[4];    

                quick.Add(instance + "," + instance2 + "," + instance3 + "," + instance4 + "," + instance5);    
            }  

            for (int i = 0; i < quick.Count; i++)
            {
                char[] delimiterChars = { ',', '\t' };
                string happy = quick[i];
                cat = happy.Split(delimiterChars);

                string element = cat[0];
                string element1 = cat[1];
                string element2 = cat[2];
                string element3 = cat[3];
                string element4 = cat[4];

                list.Add(new TextBox());
                list[i].Text = element;
                list[i].Location = new System.Drawing.Point(53, location);
                list[i].Size = new System.Drawing.Size(441, 22);

                labellist.Add(new Label());
                labellist[i].Text = "Status";
                labellist[i].Location = new System.Drawing.Point(520, location2);
                labellist[i].Size = new System.Drawing.Size(48, 17);                

                instancef.Invoke((MethodInvoker)delegate { instancef.Controls.Add(list[i]); });

                SessionOptions sessionOptions = new SessionOptions
                {
                     Protocol = Protocol.Sftp,
                     HostName = element1,
                     UserName = element2,
                     Password = element3,
                     SshHostKeyFingerprint = element4
                };

                try
                {
                    using (Session session = new Session())
                    {
                        session.Open(sessionOptions);

                        if (session.Opened == true)
                        {
                            Console.WriteLine(element + " - " + "Connection Opened");                               
                            labellist[i].BackColor = Color.Green; 
                        }
                        session.Close();
                    }    
                 }
                 catch (Exception ex)
                 {
                    Console.WriteLine(element + " Error");
                    labellist[i].BackColor = Color.Red;

                    UdpClient udpClient = new UdpClient();
                    udpClient.Connect(element1, 50);
                    Console.WriteLine(element1 + "REBOOT");
                    Byte[] senddata = Encoding.ASCII.GetBytes("reboot");
                    udpClient.Send(senddata, senddata.Length);
                    udpClient.Send(senddata, senddata.Length);
                    udpClient.Send(senddata, senddata.Length);
                }
                // Console.WriteLine(element1);
                Console.WriteLine(element + " - Connection Closed");
                instancef.Invoke((MethodInvoker)delegate { instancef.Controls.Add(labellist[i]); });
                location = location + 60;
                location2 = location2 + 60;
            }    
        } 
    }
}

i used a really poor method to solve my issue whihc is this

 if(i == 0)
                {

                    instancef.Invoke((MethodInvoker)delegate { instancef.Controls.Clear(); });
                }

However now the rest of the labels i have inputted that are not part of the loop disappear now as well, is there a way to keep them, without them disappearing as soon as the loop starts

Answer 1

You cannot do lengthy operations, like connecting to a remote server, on the GUI thread.

That blocks window update.