Question

In my code below I am taking files that are being dragged and dropped onto a button on my form, and processing them with a thread. I want to be able to have each thread complete it’s operation before the foreach loop is continued and processes the next file.

I tried a

testthread().Join();

right after the

new Thread(()…

but it gets an error because it wants me to pass the same parameters that I pass to the testthread when I initially start the thread.

Can someone please show me the command and syntax I would use to accomplish the thread joining?

private void btnClick_DragDrop(object sender, DragEventArgs e)
{
    string[] file = (string[])e.Data.GetData(DataFormats.FileDrop);

    string ButtonName = "TestButton"

    string[] files = new string[10];

    files = (string[])e.Data.GetData(DataFormats.FileDrop);


    foreach (string file in files)
    {
        FileInfo fileInfo = new FileInfo(file);

        Console.WriteLine("++  Filename: " + fileInfo.Name + "   Date of file: " + fileInfo.CreationTime + "   Type of file: " + fileInfo.Extension + "   Size of file: " + fileInfo.Length.ToString());

        string CleanFileName = System.Web.HttpUtility.UrlEncode(fileInfo.Name.ToString());

        //Start  thread
        try
        {
            Console.WriteLine("++ Calling testthread with these params: false, " + ButtonName + "," + CleanFileName + "," + file);

            new Thread(() => testthread(false, ButtonName, CleanFileName, file)).Start();

            testthread().Join(); //THIS DOES NOT WORK BECAUSE IT WANTS THE PARAMETERS THAT THE THREAD IS EXPECTING.  WHAT CAN I PUT HERE SO IT WAITS FOR THE THREAD TO FINISH BEFORE CONTINUING THE FOREACH LOOP ?
         }
         catch (Exception ipwse)
         {
         Console.WriteLine(ipwse.Message + " " + ipwse.StackTrace);
         }
     }
}
public void testthread(bool CalledfromPendingUploads, string ButtonName, string CleanFileName, string FilePath)
{
    //My Code to do the file processing that I want done.  I do not want multiple threads to run at once here.  I need the thread to complete, then the foreach loop to continue to the next file and then start another thread and wait, etc...
}

Answer 1

If you are doing things serially, why do you need separate threads at all?

Thread t = new Thread(() => testthread(false, ButtonName, CleanFileName, file));
t.Start();
t.Join();

Edit:

Also it looks like you are executing your foreach loop on the UI thread – this will block the UI thread and is generally not a good thing to do for a long running operation. I’d suggest you move the looping code into a separate method that you execute on another thread, also get rid of the separate thread for each file processing.