Android Question FTP - how to wait till file is downloaded?

[MoraviaVenus]

Hi community,

I am struggling one week already with the problem, how to handle the end of FTP download process.

I have code like this, where I just download file and read first line of it.

Sub Activity_Create(FirstTime As Boolean)

    storage = File.DirRootExternal
    FTP.Initialize("FTP", FTPServer, 21, "UserName", "Password")   

    TheDownloadFunction

End Sub

Sub TheDownloadFunction

    Dim content as String
    Dim del as Boolean

    {some code...}

    ProgressDialogShow("Downloading file...")

    DownloadSelectedFile

    txtReader.Initialize(File.OpenInput(storage, downloadedFile))
    content = txtReader.ReadLine
    txtReader.Close

    del = File.Delete(storage, downloadedFile)

End Sub

Sub DownloadSelectedFile()
  
    FTP.DownloadFile(ftpFolder & downloadedFile, False, storage, downloadedFile)
  
End Sub

Sub FTP_DownloadProgress (ServerPath As String, TotalDownloaded As Long, Total As Long)
  
    Dim str As String
    str = "Downloaded " & Round(TotalDownloaded / 1000) & " kB"
  
    If Total > 0 Then str = str & " out of " & Round(Total / 1000) & "KB"
    Log(str)
  
End Sub

Sub FTP_DownloadCompleted (ServerPath As String, Success As Boolean)

    ProgressDialogHide
  
End Sub

Now, when function

DownloadSelectedFile

is called, code immediately goes ahead and executes next line

txtReader.Initialize(File.OpenInput(storage, downloadedFile))

and consequently next line

content = txtReader.ReadLine

, where it crashes with error message: java.io.FileNotFoundException: ... open failed: ENOENT (No such file or directory). It seems to me, that just after that, the requested file is downloaded and available for reading...

Please, how can I force the code to wait till the file is downloaded and just afterwards to run ahead?

BTW, another problem, variable "del" is True after executing File.Delete(storage, downloadedFile) and deleting downloadedFile, but, the file is still in storage directory... Any ideas why?

Thank you

 

[DonManfred]

Have a look at this example. It may of help.

Instead of multiple files you just download one...

 

[MoraviaVenus]

Hi DonManfred,

thank you for hint. I checked your code and I see, that command FTP.DownloadFile is the last command in Activity_Create, and when your download finishes successfully, you process the rest of code in Sub FTP_DownloadCompleted. On the other hand, in my code, after the download finishes, the code in parent procedure continues...

Is my logic of code basicly wrong? Should I always handle the dependent code inside of Sub FTP_DownloadCompleted?

FYI, I use Sub DownloadSelectedFile() from 4 different places, with different file names and different purpose (so handling the dependent code inside of Sub FTP_DownloadCompleted is a complication for me).

Thank you.

 

[DonManfred]

On the other hand, in my code, after the download finishes, the code in parent procedure continues...

No, that´s wrong. You START the download; which is asynchronous btw...
The code following

 DownloadSelectedFile

is executed imediatly after STARTING the download. Usually the download is not finished at this moment... You need to overthink your strategy.

Start the download and wait for the download to finish.

Is my logic of code basicly wrong? Should I always handle the dependent code inside of Sub FTP_DownloadCompleted?

It must NOT directly inside this sub. you could create a sub for the work which should be done after downloading.

sub todoafterdownload
    txtReader.Initialize(File.OpenInput(storage, downloadedFile))
    content = txtReader.ReadLine
    txtReader.Close
    del = File.Delete(storage, downloadedFile)
end sub

and then just call

todoafterdownload

when download is finished from

FTP_DownloadCompleted

FYI, I use Sub DownloadSelectedFile() from 4 different places, with different file names and different purpose (so handling the dependent code inside of Sub FTP_DownloadCompleted is a complication for me).

You must keep in mind that downloads are asynchronous (like httputils jobs)