Live Data vs Observables in Android

MobiTalk Chennai - Mobile Developers Meetup

Youtube Link:
https://youtu.be/DEjgNQ6lOAc

Discord Community (Join us here for latest updates):
http://bit.ly/mobitalkchat

Topic:
Live Data vs Observables in Android

About the Event:
MobiTalk is a Mobile Meetup focused on both Android and iOS developers. This meetup is organised currently in Chennai.

Join us for the first session of MobiTalk meetup where you can learn and explore things related mobile app development.

Date of Event:
Sat, May 25, 2019 10:30 AM – 12:30 PM IST

About the Presenter:
Jyoti Dubey (@its_jaede) is working as a Product Developer @ FreshWorks.

Transcript

1. JYOTI DUBEY Android Developer- Freshworks Livedata vs Observables
2. MVP vs MVVM
3. Activity-Viewmodel Lifecycle
4. Motivation
5. Lifecycle And Config changes • Fetch something over the network • Show loading status • Display the result
6. Lifecycle And Config changes • Fetch something over the network • Show loading status • Display the result
8. View View Model
10. Activity-Viewmodel Lifecycle
12. Why this exception?
13. IllegalStateException: Can not perform this action after onSaveInstanceState
14. Why? • UI State cannot be changed after onSaveInstanceState() • Fragment transaction are UI States • Applies to views
15. Possible solutions? • commitAllowingStateLoss()? • Wait until the activity comes in the safe state
16. Possible solutions? • commitAllowingStateLoss()? • Wait until the activity comes in the safe state
17. Livedata? • Announced in Google IO’2017 • Lifecycle aware • Works with jetpack components
18. private void load() { compositeDisposable.add(repository.fetchUsers() .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(user -> isApiFetchSuccessfulSubject.onNext((!user.name.isEmpty()))); } } private void load() { compositeDisposable.add(repository.fetchUsers() .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe(user -> isApiFetchSuccessfulLiveData.setvalue(!user.name.isEmpty()))); } }
19. Observable vs Livedata subscription Comparison private void observeForDataChanges() { viewModel.isApiFetchSuccessfulLiveData.observe(this,result->{ if(result){ ApiFetchSuccessDialog dialog = new ApiFetchSuccessDialog(); dialog.show(getFragmentManager(), ApiFetchSuccessDialog.TAG); } }); } private void observeForDataChanges() { compositeDisposable.add(viewModel.isApiFetchSuccessfulSubj ect.subscribe(result->{ if(result){ ApiFetchSuccessDialog dialog = new ApiFetchSuccessDialog(); dialog.show(getFragmentManager(), ApiFetchSuccessDialog.TAG); } })); } @Override protected void onDestroy() { compositeDisposable.dispose(); super.onDestroy(); }
21. LIVE DATA BEHAVIORSUBJECT ‣ Caches at most one item ‣ Re-emit last known item ‣ Emission always happens on main thread ‣ Emits only when life cycle owner is in safe state ‣ Disposes automatically when the lifecycle owner is destroyed ‣ No error channel ‣ Less transformation operators ‣ Caches at most one item ‣ Re-emit last known item ‣ Can be observed on any thread ‣ Emits irrespective of life cycle ‣ Has to be disposed manually ‣ Has error channel ‣ Abundance of transformation operators
22. LIVE DATA BEHAVIORSUBJECT ‣ Caches at most one item ‣ Re-emit last known item ‣ Emission always happens on main thread ‣ Emits only when life cycle owner is in safe state ‣ Disposes automatically when the lifecycle owner is destroyed ‣ No error channel ‣ Less transformation operators ‣ Caches at most one item ‣ Re-emit last known item ‣ Can be observed on any thread ‣ Emits irrespective of life cycle ‣ Has to be disposed manually ‣ Has error channel ‣ Abundance of transformation operators
23. Drawbacks • Live data transformations happen on main thread • Operators supported are: map(), flatmap(), distinctUntilChanged()
24. • Live data should appear in last layer of UI Update • Rx excels in transformation operators and multi-threading. • Choose Rx if user is not going to touch the UI much • Work by combining observable and live data. Conclusion
25. Questions? https://github.com/jyotid https://twitter.com/its_jaede