Wait until download is complete before starting other tasks - vb.net

Question

I am trying to download a file, and then run some adb commands. However when downloading, i could not get it to update the progress bar using
downloadFile(url,filename)` command.
A bit of searching it said that the command was blocking the UI thread, so i decided to use Task.Run() (a solution to my previous post to run ADB Commands when it blocked the UIThread).
This made no difference. Another solution that i found is to use
downloadFileAsync(url, filename)
The progress bar is updating!
But, the ADB commands are running before the file is downloaded! They are declared after, but they are still being run before the file is downloaded, which I don't want.
Here is the code:
Private Sub btnFlashRecovery_Click(sender As Object, e As EventArgs) Handles btnFlashRecovery.Click
'Insert ommited Code here (removed to simplify question)
'id is variable obtained from a previous code that was ommited here
Dim fileName As String = "downloads/twrp-" & id & ".img"
DownloadFile(url, fileName)
'run the right commands
LabelToOutput = txtBoxRecovery
Dim commands(3, 3) As String
commands = {{"adb", "reboot bootloader", "Rebooting to bootloader"},
{"fastboot", "flash recovery" & "downloads/twrp-3.1.1-0.img", "Flashing recovery: (make sure device is plugged, otherwise it will not output anything)"},
{"fastboot", "reboot", "Rebooting device"}
}
'Task to run after
Task.Run(Sub() runComands(commands))
End Sub
Private Sub UpdateProgressBar(ByVal a As Integer)
If Me.InvokeRequired Then
Dim args() As String = {a}
Me.Invoke(New Action(Of String)(AddressOf UpdateProgressBar), args)
Return
End If
ProgressBar1.Value = CInt(a)
End Sub
Public Sub DownloadFile(urlAddress As String, location As String)
Using webClient = New WebClient()
AddHandler webClient.DownloadFileCompleted, AddressOf Completed
AddHandler webClient.DownloadProgressChanged, AddressOf ProgressChanged
Try
' Start downloading the file
webClient.DownloadFileAsync(New Uri(urlAddress), location)
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End Using
End Sub
' The event that will fire whenever the progress of the WebClient is changed
Private Sub ProgressChanged(sender As Object, e As DownloadProgressChangedEventArgs)
'Console.WriteLine(e.ProgressPercentage)
' Update the progressbar percentage only when the value is not the same.
UpdateProgressBar(e.ProgressPercentage)
End Sub
' The event that will trigger when the WebClient is completed
Private Sub Completed(sender As Object, e As AsyncCompletedEventArgs)
If e.Cancelled = True Then
MessageBox.Show("Download has been canceled.")
Else
MessageBox.Show("Download completed!")
End If
End Sub

Answer 1

Do it like this:
'Need Async keyword with the method
Private Async Sub btnFlashRecovery_Click(sender As Object, e As EventArgs) Handles btnFlashRecovery.Click
'Insert ommited Code here (removed to simplify question)
'id is variable obtained from a previous code that was ommited here
Dim fileName As String = "downloads/twrp-" & id & ".img"
'You need to AWAIT the result of the task
Await Task.Run(Sub() DownloadFile(url, fileName))
'run the right commands
LabelToOutput = txtBoxRecovery
Dim commands(3, 3) As String
commands = { {"adb", "reboot bootloader", "Rebooting to bootloader"},
{"fastboot", "flash recovery" & "downloads/twrp-3.1.1-0.img", "Flashing recovery: (make sure device is plugged, otherwise it will not output anything)"},
{"fastboot", "reboot", "Rebooting device"}
}
'Task to run after
'Await here, too, to allow the UI to remain responsive
Await Task.Run(Sub() runComands(commands))
End Sub