How to handle screen orientation change when progress dialog and background thread active?

Question

My program does some network activity in a background thread. Before starting, it pops up a progress dialog. The dialog is dismissed on the handler. This all works fine, exc

Answer 1

I've tried EVERYTHING. Spent days experimenting. I didn't want to block the activity from rotating. My scenario was:

1. A progress dialog showing dynamic information to the user. E.g.: "Connecting to server...", "Downloading data...", etc.
2. A thread doing the heavy stuff and updating the dialog
3. Updating the UI with the results at the end.

The problem was, when rotating the screen, every solution on the book failed. Even with the AsyncTask class, which is the correct Android way of dealing with this situations. When rotating the screen, the current Context that the starting thread is working with, is gone, and that messes up with the dialog that is showing. The problem was always the Dialog, no matter how many tricks I added to the code (passing new contexts to running threads, retaining thread states through rotations, etc...). The code complexity at the end was always huge and there was always something that could go wrong.

The only solution that worked for me was the Activity/Dialog trick. It's simple and genius and it's all rotation proof:

1. Instead of creating a Dialog and ask to show it, create an Activity that has been set in the manifest with android:theme="@android:style/Theme.Dialog". So, it just looks like a dialog.

2. Replace showDialog(DIALOG_ID) with startActivityForResult(yourActivityDialog, yourCode);

3. Use onActivityResult in the calling Activity to get the results from the executing thread (even the errors) and update the UI.

4. On your 'ActivityDialog', use threads or AsyncTask to execute long tasks and onRetainNonConfigurationInstance to save "dialog" state when rotating the screen.

This is fast and works fine. I still use dialogs for other tasks and the AsyncTask for something that doesn't require a constant dialog on screen. But with this scenario, I always go for the Activity/Dialog pattern.

And, I didn't try it, but it's even possible to block that Activity/Dialog from rotating, when the thread is running, speeding things up, while allowing the calling Activity to rotate.