Question

The following codes is moving a file as long as the file doesn’t already exist. If it does, it won’t move the file.

My question is regarding the File.Move. When will the msgbox display? Will it display once the file is completely moved or will it display right after the File.Move line is executed.

Depending on the file size, it may take awhile to move the file and thus I don’t want the msgbox to display until the file is moved completely.

Is there a better way of doing this?

        For Each foundFile As String In My.Computer.FileSystem.GetFiles("C:\Temp\", FileIO.SearchOption.SearchAllSubDirectories, "*.zip")
            Dim foundFileInfo As New System.IO.FileInfo(foundFile)

            If My.Computer.FileSystem.FileExists("C:\Transfer\" & foundFileInfo.Name) Then
                Msgbox("File already exists and will not moved!")
                Exit Sub
            Else
                File.Move(foundFile, "C:\Transfer\" & foundFileInfo.Name)
                Msgbox("File has been moved!")
            End If
        Next

Answer 1

Accordingly to this source, the File.Movecall is synchronous, which means that your msgbox will be shown only after the file is moved, regardless of its size.

For completeness, if you don’t want to block the UI, you can try something like this:

' This must be placed outside your sub/function
Delegate Sub MoveDelegate(iSrc As String, iDest As String)

' This line and the following go inside your sub/function
Dim f As MoveDelegate = AddressOf File.Move

' Call File.Move asynchronously
f.BeginInvoke(
    foundFile, 
    "C:\Transfer\" & foundFile, 
    New AsyncCallback(Sub(r As IAsyncResult)
                          ' this code is executed when the move is complete
                          MsgBox("File has been moved!")
                      End Sub), Nothing)

or you can explore the new async / await instructions.