Arrays and variables clears itself after a end sub in VB.net - asp.net

Question

I am writing a times tables program in ASP.net and I need some help. The problem I am experiencing is that when the button sub ends and the screen pops up again for user input, all the arrays and variables are now set to nothing or 0.
Is there are way to keep all the values for variables after a sub ends and to use them later on?
Any help will be appreciated.
Public Class PickTimesTables
Inherits System.Web.UI.Page
Dim count As Integer = 0
Dim NumberQ As Integer
Dim RandomN As Integer
Dim FirstNumber() As Integer
Dim FirstNumberTemp() As Integer
Dim SecondNumber() As Integer
Dim correctAnswers As Integer
Dim inc As Integer = 0
Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
PanelQuestion.Visible = False
PanelAnalysis.Visible = False
End Sub
Protected Sub btnTest_Click(sender As Object, e As EventArgs) Handles btnTest.Click
PanelQuestion.Visible = True
lblOperator.Text = "X"
If chktimes1.Checked = False And chktimes2.Checked = False And chktimes3.Checked = False And chktimes4.Checked = False And chktimes5.Checked = False And chktimes6.Checked = False And chktimes7.Checked = False And chktimes8.Checked = False And chktimes9.Checked = False And chktimes10.Checked = False And chktimes11.Checked = False And chktimes12.Checked = False Then
MsgBox("Pick a Times Table to be Tested for..")
ElseIf txtNoQuestion.Text = "" Then
MsgBox("Pick the Number of Question for the test")
Else
NumberQ = txtNoQuestion.Text
count = 0
If chktimes1.Checked Then
count = count + 1
End If
If chktimes2.Checked Then
count = count + 1
End If
If chktimes3.Checked Then
count = count + 1
End If
If chktimes4.Checked Then
count = count + 1
End If
If chktimes5.Checked Then
count = count + 1
End If
If chktimes6.Checked Then
count = count + 1
End If
If chktimes7.Checked Then
count = count + 1
End If
If chktimes8.Checked Then
count = count + 1
End If
If chktimes9.Checked Then
count = count + 1
End If
If chktimes10.Checked Then
count = count + 1
End If
If chktimes11.Checked Then
count = count + 1
End If
If chktimes12.Checked Then
count = count + 1
End If
If txtNoQuestion.Text = 0 Then
MsgBox("You cannot have a test with 0 Questions")
Else
ReDim FirstNumberTemp(count - 1)
For i = 0 To count - 1
If chktimes1.Checked Then
FirstNumberTemp(i) = 1
chktimes1.Checked = False
ElseIf chktimes2.Checked Then
FirstNumberTemp(i) = 2
chktimes2.Checked = False
ElseIf chktimes3.Checked Then
FirstNumberTemp(i) = 3
chktimes3.Checked = False
ElseIf chktimes4.Checked Then
FirstNumberTemp(i) = 4
chktimes4.Checked = False
ElseIf chktimes5.Checked Then
FirstNumberTemp(i) = 5
chktimes5.Checked = False
ElseIf chktimes6.Checked Then
FirstNumberTemp(i) = 6
chktimes6.Checked = False
ElseIf chktimes7.Checked Then
FirstNumberTemp(i) = 7
chktimes7.Checked = False
ElseIf chktimes8.Checked Then
FirstNumberTemp(i) = 8
chktimes8.Checked = False
ElseIf chktimes9.Checked Then
FirstNumberTemp(i) = 9
chktimes9.Checked = False
ElseIf chktimes10.Checked Then
FirstNumberTemp(i) = 10
chktimes10.Checked = False
ElseIf chktimes11.Checked Then
FirstNumberTemp(i) = 11
chktimes11.Checked = False
ElseIf chktimes12.Checked Then
FirstNumberTemp(i) = 12
chktimes12.Checked = False
End If
Next
ReDim FirstNumber(NumberQ - 1)
For i = 0 To NumberQ - 1
Randomize()
RandomN = FirstNumberTemp(Int(Rnd() * count))
FirstNumber(i) = RandomN
Next
ReDim SecondNumber(NumberQ - 1)
For i = 0 To NumberQ - 1
Dim rn As New Random(Now.Millisecond)
RandomN = rn.Next(1, 13)
SecondNumber(i) = RandomN
Next
lblFirstN.Text = FirstNumber(0)
lblSecondN.Text = SecondNumber(0)
End If
End If
End Sub
Protected Sub txtInput_TextChanged(sender As Object, e As EventArgs) Handles txtInput.TextChanged
NumberQ = txtNoQuestion.Text
If txtInput.Text = FirstNumber(inc) * SecondNumber(inc) Then
lblFirstN.Text = FirstNumber(inc + 1)
lblSecondN.Text = SecondNumber(inc + 1)
correctAnswers = correctAnswers + 1
txtInput.BackColor = Drawing.Color.Green
Else
txtInput.BackColor = Drawing.Color.Red
lblFirstN.Text = FirstNumber(inc + 1)
lblSecondN.Text = SecondNumber(inc + 1)
End If
End Sub
End Class

Answer 1

This is a common mistake for newcomers to ASP.Net Webforms. There is this idea that your page class instance lives for an entire session, for all of a user's interactions with the page in the browser. This does not happen. Any interaction with your page that causes an event to fire creates a new postback from the client to the server, and every postback uses a brand new instance of the Page class. By the time the user sees your page in their browser, whatever Page object you used to render the html for that view has already been destroyed and garbage collected.
There are some things you can do to get around this, like putting variables in the Session, URL, or ViewState, but often you need to completely re-think your approach to something that is more natural for a web site.
Additionally, you'll want to re-think handling a TextChanged event in your VB.Net code. Generally speaking, TextChanged events need to return to the user in 25-40 milliseconds, or the view will feel extremely sluggish. It's not usually a problem when the program is running right there on the user's computer, and has all the memory and CPU power of that workstation available. It's a whole other story for web sites, where you might have an 80ms delay before the request even reaches the server and another 80ms for the response, all before doing any processing, and the server is sharing it's CPU and memory resources to support as many users as you can fit.
Instead, look into using a javascript event for that processing, and only validate the text in your VB.Net code when the user finally tries to submit or save the end result.
Finally, those calls to the MsgBox() function need to go, too. It only seems to work on your system because your web server is on the same machine as the web browser. When you go to actually put this on a real server and test from a different place, those message will display on the server, not in the user's web browser.

Answer 2

They'll all be reset because that's the stateless nature of the web. They don't keep their values because each subsequent time you view that page (or step through it using the debugger), it's a new request.
You should google storing asp.net variables in ViewState or Session, i.e. ViewState-backed properties.