The simplest thread example in the world

Download source code - 10.3 KB

Introduction

This article shows the difference between running a function on the main form thread, and on a separate thread. You can thus still interact with the form even though the code would normally 'block' execution.

Background

I helped a mate out and thought this is a good example as it demonstrates just threading and nothing else.

Using the code

Just download and compile the code. Here is the important code (about five lines below, and is taken from the source code comments):

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    } //do it in another thread

    private void button1_Click(object sender, EventArgs e)
    {
        //create a new instance of YOUR thread class
        ThreadExample te = new ThreadExample();
        te.iIntervalInMilliSeconds = 5000;

        //run the ThreadExample.Start() function in a new thread
        Thread th = new Thread(new ThreadStart(te.Start));
        th.Start();
    }
    //do it in the same thread as your form
    private void button2_Click(object sender, EventArgs e)
    {
        ThreadExample te = new ThreadExample();
        te.iIntervalInMilliSeconds = 5000;
        te.Start();
    }
}

//you need to use classes for this because you probably want
//to set some values before you run the main function 
//(which cant have parameters - unlucky!)
public class ThreadExample
{
    public int iIntervalInMilliSeconds = 1000;
    //all this does is beep every so often - you can still 
    //interact with the form if this runs on another thread
    public void Start()
    {
        for (int iLoop = 0; iLoop < 3; iLoop++)
        {
            Interaction.Beep();
            Thread.Sleep(iIntervalInMilliSeconds);
        }
        MessageBox.Show("End");
    }
}

//NB - if you want to interact with the form from another thread
//you will have to look up 'invoke' as this runs the function you want, but
//on the main form thread (you could have lots of threads all trying 
//to access the same control, so this way, the requests get 'queued up' sort of!