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

namespace WindowsApplication2
{
    public partial class Form1 : Form
    {
        public   Thread trd;//定义一个线程
        private  void ThreadTask()
        {
            int stp;
            int newval;
            Random rnd = new Random();

            while (true)
            {
                stp = this.progressBar1.Step * rnd.Next(-1, 2);
                newval = this.progressBar1.Value + stp;

                if (newval > this.progressBar1.Maximum)
                {
                    newval = this.progressBar1.Maximum;
                }
                else if (newval < this.progressBar1.Minimum)
                {
                    newval = this.progressBar1.Minimum;
                }
                //this.progressBar1.Value = newval;
                this.progressBar1.Value = newval;//就是这里的问题
                    Thread.Sleep(100);
                
            }
        }
        public Form1()
        {
            InitializeComponent();
        
        }

        private void button1_Click(object sender, EventArgs e)
        {
            MessageBox.Show("this is main threading");
        }

        private void Form1_Load(object sender, EventArgs e)
        {
    
                Thread trd = new Thread(new ThreadStart(this.ThreadTask));
                trd.IsBackground = true;
                trd.Start();

        }
    }
}