Use strong references to callbacks in Stripe and CustomerSession #863
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**Summary** `Stripe` and `CustomerSession` methods accept callback objects that typically hold references to `Activity` objects. The best practice in Android is that references to `Activity` objects should be weakly held for long-running background tasks, because the `Activity` may go away (e.g. user leaves activity before task is complete). The change was first introduced in #666. After this change, users began reporting that callback objects would mysteriously be garbage-collected by the OS. I was able to reproduce this as well, and found a work-around by moving anonymous inline classes to instance variables - see 2b74328. Android will GC objects that are no longer strongly referenced. When inlined, the callback objects were no longer strongly referenced once the method completed (e.g. in 2b74328, the left-side of `AddSourceActivity#onActionSave`); moving these objects to be instance variables meant that they were now strongly-referenced by the Activity. This explains why the GC issues were resolved with this change. In conclusion, the correct solution is to have the callback objects weakly-reference `Activity` objects, rather than weakly-reference the callback objects themselves. **Motivation** ANDROID-340
jemerick-stripe
approved these changes
Apr 11, 2019
Merged
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Summary
StripeandCustomerSessionmethods accept callback objectsthat typically hold references to
Activityobjects. The bestpractice in Android is that references to
Activityobjectsshould be weakly held for long-running background tasks, because
the
Activitymay go away (e.g. user leaves activity before taskis complete). The change was first introduced in #666.
After this change, users began reporting that callback objects
would mysteriously be garbage-collected by the OS. I was able
to reproduce this as well, and found a work-around by moving
anonymous inline classes to instance variables - see 2b74328.
Android will GC objects that are no longer strongly referenced.
When inlined, the callback objects were no longer strongly
referenced once the method completed (e.g. in 2b74328, the
left-side of
AddSourceActivity#onActionSave); moving theseobjects to be instance variables meant that they were now
strongly-referenced by the Activity. This explains why the GC
issues were resolved with this change.
In conclusion, the correct solution is to have the callback
objects weakly-reference
Activityobjects, rather thanweakly-reference the callback objects themselves.
Motivation
ANDROID-340
Testing
Manually tested