Question

I’m trying to get my user interface to react to events (like button presses, thread completions, etc.) in real time in Android (obviously).

I have a button layout, and one of the buttons is used to copy an unknown number of files from a remote computer using FTP. The FTP part of all this is working very well, but I just cannot find a way to let the user know the state of things:

The states, as I see them are:
1) Selected “Download Files” from “normal” menu.
2) Pressed Confirm (the download process may be quite lengthy and perhaps I don’t want to select it by mistake — however now it’s a separate thread so may need to re-think that.
3) Downloading
4) Download complete, restore normal menu

One of the things I hoped would work would be to run the FTP code in a separate thread, and by using the thread.isAlive() construction, wait for the thread to complete and change the display accordingly.

The only thing I haven’t been able to do is display that files are downloading. Regardless of what I try, the display jumps from the “Confirm Download” view to the “Normal Menu” view. (Please note, these are not Views as Android defines them in any way.)

Code follows:

Btn.setOnClickListener (new View.OnClickListener()
{
    @Override
    public void onClick (View v)
    {
        hideTempWidgets();
        Btn01.setVisibility (View.GONE);                
        Btn02.setVisibility (View.GONE);                
        Btn03.setVisibility (View.GONE);                

        verfBtn.setVisibility (View.VISIBLE);
        verfBtn.setText ("Press to Verify");
        verfBtn.setOnClickListener (null);
        verfBtn.setOnClickListener (new View.OnClickListener()
        {
            @Override
            public void onClick (View v)
            {
                runOnUiThread (new Runnable()
                {
                    public void run()
                    {
                        verfBtn.setText ("Downloading...");
                    }
                });

                Thread temp = new Thread (new Runnable()
                {
                    public void run()
                    {
                        try
                        {
                            FileTransfer.getFiles (getAddr().trim());
                        }
                        catch (SQLException e)
                        { }
                    }
                }, "ftp");

                temp.start();
                while (temp.isAlive());                                 

                verfBtn.setVisibility (View.GONE);
                Btn01.setVisibility (View.VISIBLE);
                Btn02.setVisibility (View.VISIBLE);
                Btn03.setVisibility (View.VISIBLE);
                alert (true, VIBE_BLIP);
            }
        });
    }
});

Has anybody faced this and come up with a decent solution??

What’s not happening is the setText to “Downloading…”, or at least, if it does, not when I want it to and too fast to see… Finally, what’s especially frustrating is that that command does work properly when I remove the code to run the FTP thread.

Thanks,
R.

Answer 1

This task seems to be perfect for Async Task. Basically Async Task is a Thread with a built in, thread safe component to allow you to publish updates to the UI and notify when the task is complete.
A popular idea is to show a spinner or progress bar, until the AsyncTask is complete, then dismiss it.

For more information about Async Task see: http://developer.android.com/reference/android/os/AsyncTask.html