Converting String to a DateTime or TimeValue - vb.net

Question

I have a problem trying to convert a String to a DateTime or TimeValue.
I made a little Windows Form to use as an example. Please take a look at this to see the Form:
As you can see there is a TextBox1.
Also a Timer1 with an interval of 1000 ms.
What I want is to be able to fill in a time in the textbox (like this format: 22:30:00) and when your desktop reaches this time, it will display a messagebox.
I tried several old posts and tutorials with similar problems but I can't seem to find the solution. Can anyone make a quick example using my screenshot perhaps?
This is the code someone else suggested.
Dim tsValue As TimeSpan = TimeSpan.Zero
If TimeSpan.TryParse(TextBox1.Text.Trim, tsValue) Then
If Date.Now.TimeOfDay = tsValue Then
MessageBox.Show(String.Format("Messagebox test {0}", tsValue.ToString))
End If
End If
But for some reason it does not work when I place it in my Timer.

Answer 1

Keep a variable with the target time (assuming it passes validation) and have your timer check if the target time matches the current time. Make sure your timer updates the date when the day changes (12:00 AM).
Private m_dteTime As DateTime
Private m_dteCurrentDate As Date = DateTime.Now.Date
Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
'Validation
Try
Dim strHours As String = TextBox1.Text.Substring(0, 2)
Dim strMinutes As String = TextBox1.Text.Substring(3, 2)
Dim strSeconds As String = TextBox1.Text.Substring(6, 2)
If IsNumeric(strHours) AndAlso IsNumeric(strMinutes) And IsNumeric(strSeconds) Then
m_dteTime = DateTime.Now.Date.AddHours(Convert.ToDouble(strHours)).AddMinutes(strMinutes).AddSeconds(strSeconds)
Else
m_dteTime = DateTime.MinValue
End If
Catch ex As Exception
End Try
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
If DateTime.Now.Date > m_dteCurrentDate Then
m_dteCurrentDate = DateTime.Now.Date
End If
If m_dteTime.Date = DateTime.Now.Date AndAlso m_dteTime.Hour = DateTime.Now.Hour AndAlso _
m_dteTime.Minute = DateTime.Now.Minute AndAlso m_dteTime.Second = DateTime.Now.Second Then
MsgBox("The time is now.")
End If
End Sub

Answer 2

The reason your code is not working is you're using "=" operator to compare two values which are highly unlikely to be equal. The thing is, you're entering the time value without milliseconds in your TextBox control, but the TimeOfDay function returns current time including milliseconds. Therefore, your message box never gets shown.
Now, there are multiple ways to get around this, but let's keep it simple. If you change "=" to "<=", it will work, but in that case your message box will continue to appear with each timer iteration, so you would have to disable timer right after or just before you show a message box. Depending on what are you trying to achieve, this could or could not be the solution for you.
If you need to keep the timer running, you can remove the millisecond part of the current time before comparing, which will give you one second to do the comparing. Also, in this case you should reduce timer interval to a lower value (500ms should be enough).
Also, if I may suggest, instead of TextBox, you should use DateTimePicker control with Format property set to Time and ShowUpDown property set to True. It will make your life easier as it will automate validation and also avoid uneeded conversions.