both threads update the UI ?

[AlwayzLearning]

I am new to threading, and am struggling with some simple code that displays the affects of threading as an example. The code is not originally mine and I don't know who the credit goes to for making it. The example I have allows for a separate thread to update the UI, but when i go to execute a different thread while the first one is running it stops updating the UI until they are both done executing. I would like to be able to see both threads update the UI simultaneously without hanging up the updates.
After reading several forums and such I think I should be looking into Asynchronous threading. Is there anyway somebody here can shed some light on this for me and possibly point out corrections that would need done to make this work?
Any help would be greatly appreciated! Thank you in advance!
(Also I don't know how to post blocks of code like the above examples... Code is pasted below)

Imports System.Threading
Public Class Form1
    Delegate Sub callback1(ByVal [text] As String)
    Delegate Sub callback2(ByVal [text] As String)
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim count As New Thread(New ThreadStart(AddressOf count1))
        count.Start()


    End Sub
    Private Sub count1()
        Dim rna As New Random
        Dim i As Integer
        i = 0
        Do Until i = 1000
            i = i + 1
            setText1(rna.Next(1, 1000))
        Loop
    End Sub
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Dim count As New Thread(New ThreadStart(AddressOf count2))
        count.Start()
    End Sub
    Private Sub count2()
        Dim rna As New Random
        Dim i2 As Integer
        i2 = 0
        Do Until i2 = 1000
            i2 = i2 + 1
            setText2(rna.Next(1, 1000))
        Loop
    End Sub
    Private Sub setText1(ByVal [text] As String)
        If Me.TextBox1.InvokeRequired = True Then
            Dim d As New callback1(AddressOf setText1)
            Me.Invoke(d, New Object() {[text]})
        Else
            TextBox1.Text = [text]
            Label1.Text = [text]
        End If
    End Sub
    Private Sub setText2(ByVal [text] As String)
        If Me.TextBox2.InvokeRequired = True Then
            Dim d As New callback2(AddressOf setText2)
            Me.Invoke(d, New Object() {[text]})


        Else
            TextBox2.Text = [text]
            Label2.Text = [text]
        End If
    End Sub
End Class

 

[jmcilhinney]

With both loops running, there's just too much going on for the form to have time to refresh the UI. In fact, you should probably be able to see that with just one loop. I tried running your code and, if I clicked one Button, I saw the corresponding Label refresh rapidly but the TextBox was refreshed a few times at most. After setting the Text of a TextBox or Label, call its Refresh method to force it to refresh. You will then see both TextBoxes and both Labels refresh each and every time.

By the way, it is pointless to declare two delegates with the same signature. A single delegate type can be used to invoke any method with the same signature so you only need one delegate type there. In fact, you don't need to declare any delegate of your own because you can simply use Action(Of String).