Focus on a TextBox based on its input check - vb.net

Question

I want my program to check whether the inputs in a TextBox meet certain condition. If the target condition is not met, the cursor should focus back on that particular TextBox.
My code:
Private Sub ButtonSubmit_Click(sender As Object, e As EventArgs) Handles ButtonSubmit.Click
EnterVotes.LabelCan1.Text = CandName1.Text
EnterVotes.Labelcan2.Text = CandName2.Text
EnterVotes.LabelCan3.Text = CandName3.Text
EnterVotes.LabelCan4.Text = CandName4.Text
EnterVotes.LabelCan5.Text = CandName5.Text
If CandName1.Text = "" Then
MessageBox.Show("Please enter a name in Candidate 1")
End If
loading.Show()
Me.Hide()

Answer 1

If CandName1.Text = "" Then //Show your message here // CandName1.focus()//to return to that textbox Else //Show your
message here End If
use the method focus() to return and re-write into that textbox

Answer 2

It is actually quite simple
just check if the value of the text is > 1
then put focus on the textbox
heres an example
if txtbox.text.value < 1 then
messagebox.show("You must enter data for textbox")
txtbox.focus()
end if
and then continue method for each text box you are working with

Answer 3

Could get fancy and use some linq to go threw your names.
Dim Candidate() As TextBox
Candidate = Me.Controls.OfType(Of TextBox)().Where(Function(c) c.Name.Contains("CandName")).ToArray()
Dim i As Integer = 0
While i < Candidate.Count
If(Candidate(i).text.value < 1)
MessageBox.Show("Please enter a name in Candidate " & (i + 1).ToString())
Candidate(i).Focus()
Exit While
End If
i += 1
End While
This way you can check all your candidates in one shot. This is untested code, but I think it should work.
You can play around with this and edit however you please it's pretty flexible at this point.

Answer 4

I think this might be the way but not very efficient.
If CandName1.Text = "" Then
MessageBox.Show("Please enter a name in Candidate 1")
CandName1.Focus()
Else
CandName2.Focus()
End If
If CandName2.Text = "" Then
MessageBox.Show("Please enter an name in Candidate 2")
CandName3.Focus()
Else
CandName3.Focus()
End If
If CandName3.Text = "" Then
MessageBox.Show("Please enter a name in Candidate 3")
CandName3.Focus()
Else
CandName4.Focus()
End If
If CandName4.Text = "" Then
MessageBox.Show("Please enter a name in candidate 4")
CandName4.Focus()
Else
CandName5.Focus()
End If
If CandName5.Text = "" Then
MessageBox.Show("Pleae enter a name in candidat 5")
CandName5.Focus()
Else
loading.Show()
End If

Answer 5

If String.IsNullOrWhitespace( CandName1.Text ) Then
MessageBox.Show("Please enter a name in Candidate 1")
CandName1.Focus()
Return
End If
... for all five
loading.Show()
Me.Hide()
You want to make sure to exit this early with the Return statements so you don't get to the code:
loading.Show()
Me.Hide()