Notes on opportune moments to do "stuff" in the Android Lifecycle

android_lifecycle_recommendations.md

• In general you want to try and put things in onStart and onStop for logical start and stops.

Activity

onCreate

• Dagger inject self into graph
• setContentView(R.layout.xxx)
• Butterknife.bind(this)
• RxJava CompositeSubscription.add (if NON UI related work being done)
• realm = Realm.getDefaultInstance();

onStart

• EventBus register // why not onResume + onPause you ask?

onResume

• RxJava CompositeSubscription.add (if ui related work being done)

onPause

• RxJava CompositeSubscription.clear (if ui related work being done)

onStop

• EventBus unregister

onDestroy

• Dagger "Activity" scoped graph destruction
• RxJava CompositeSubscription.clear (if NON UI related work being done)
• realm.close();

Fragment (DialogFragment etc.)

onAttach(Context) (prev.Activity)

• Dagger inject self into graph
• setCallbackOrListener(activity) - when you want to communicate back to the activity

Warning: lifecycle callpoint is subtly different now. onAttach(Context) is called later than onAttach(Activity) and so if you expected the injection to have happened before certain callbacks like onViewCreated this is not the case (e.g. API 19)

onCreateView

• view = Inflate.inflation
• ButterKnife.bind(this, view);
• realm = Realm.getDefaultInstance();

onStart

• EventBus register

onResume

• RxJava CompositeSubscription.add (if ui related work being done)

onPause

• RxJava CompositeSubscription.clear (if ui related work being done)

onStop

• EventBus unregister

onDestroy

• LeakCanary MyApp.getRefWatcher().watch(this);

onDestroyView

• ButterKnife.unbind(this);
• realm.close();

View

onFinishInflate

• Butterknife.bind(this)

onAttachedToWindow

• RxJava CompositeSubscription.add

onDetachedFromWindow

• RxJava CompositeSubscription.clear

Application

• LeakCanary Refwatcher = LeakCanary.install(this);
• Dagger ObjectGraph.create

ViewHolder (for RecyclerViews, ListViews etc.)

ViewHolder (Constructor)

• Butterknife.bind(this. itemView)

Very nice document, I only have a concern, I would not recommend the following or at least I would add a warning:

View

onAttachedToWindow

• RxJava CompositeSubscription.add

onDetachedFromWindow

• RxJava CompositeSubscription.unsubscribe

When the app is pushed to the background, the view won't be detached from the window. So you need to be careful not to do some UI update like open new activity in this callback, because it is not guarantee that the app is in the foreground.