Android: Window leaks on finish

Question

I have read the other window leak posts and have tried what what suggested there to no avail.

I have 3 activities: A, B, and C. Activity A gathers information from the user. Activity B displays a spinning ProgressDialog while it communicates with a server on another thread. When the thread finishes, it dismisses the ProgressDialog and starts the next activity. Activity C displays the information from the server to the user. Activity B is set up so that when the user hits back from C, they fall back to A.

It is important that these tasks be in separate Activities.

As of now the app successfully does what it is supposed to in most cases, except in the following scenario: If the user changes the orientation while in activity C before returning to Activity A, the app crashes due to a window leak.

• I am dismissing the ProgressDialog inthe onPause() of Activity B before istart C.
• I have tried dismissing the ProgressDialog on the main thread using a handler as well as in the separate thread.
• When the user does not change the orientation in C, no window leak occurs.

Any ideas? TIA

Answer 1

This often happens where ProgressDialogs are used. I experimented with ProgressDialog a while back and found the thing to do was dismiss() it from onPause() and create it anew from onResume(). The background task obviously needs to survive your Activity & dialog so I used onRetainNonConfigurationInstance() to pass the task instance from the destroyed Activity to the new one.

An alternative, cheatier workaround might be to simply prevent your Activity from being destroyed and created anew merely because the screen orientation changed. Do this by adding android:configChanges="orientation" to the tag(s) in your AndroidManifest.xml.

Answer 2

I solved my problem by completely changing how i handled everything. I now have only two activities (A and B) and display the ProgessDialog in activity B while handling the savedInstanceState as needed in order to work around the problem.

Even though I have fixed the problem on my app, I still dont know why it was occuring before and would like to learn more about window leaks and why i was having problems. If anyone knows more about the problem i was having, please post as I'm sure there are others with the same problem.

Thanks

Answer 3

Not sure if this was related to your specific problem, but I had a similar issue which had to do with leaky windows for dialogs that are created in the onCreate method of an activity. So if your activity starts up showing a dialog, and you do a config change, the OS remembers which dialogs were shown, so when the activity is killed & restarted, the OS attempts to restore your old dialog while your activity tries to show the same dialog again (since it's in onCreate). I found by only showing the dialog during onCreate if it's not a config change (ie. savedInstanceState != null), the leaky window problem went away.