Android Architecture Components Room, LiveData & ViewModel

Sesión del mes de Agosto del MeetUp de Medellín Android, abordando los nuevos Android Architecture Components, mostrando tanto el detalle técnico como el de implementación con un ejemplo funcional.
These slides correspond to Medellin Android's August session, tackling new Android Architecture Components and showing their technical details as well as implementation ones with a functional example.

Transcript

1. Android Architecture Components Room, LiveData & ViewModel Carlos Daniel Munoz - Android Dev @cdmunozi cdmunoz@gmail.com August 9th - 2017 @MedellinAndroid
2. New architecture guidelines for Android Development
3. 3 The journey ...
4. 4 Android Development Process
5. 5 Android Development Process • Put all your code into Activities files
6. 6 Android Development Process • Put all your code into Activities files • Occasionally, move some stuff into AsyncTasks if error NetworkOnMainThreadException
7. 7 Android Development Process • Put all your code into Activities files • Occasionally, move some stuff into AsyncTasks if error NetworkOnMainThreadException • Unit tests and instrumentation tests → hard to do, read and maintain
8. 8 Evolution • Patterns: ◦ MVC ◦ MVP ◦ MVVM ◦ . ◦ . ◦ . • 3rd party Libraries
9. 9 Had Google and Android Dev team shared some guidance?
10. 10 No :(
11. Google I/O 2017 Android Architecture Components - AAC
12. 12 What are AAC framework?
13. 13 What are AAC framework? • Libraries
14. 14 What are AAC framework? • Libraries • Guidelines
15. 15 What are AAC framework? • Libraries • Guidelines • Common scenarios in apps dev
16. 16 What are AAC framework? • Libraries • Guidelines • Common scenarios in apps dev • Aims:
17. 17 What are AAC framework? • Libraries • Guidelines • Common scenarios in apps dev • Aims: ◦ Reduce boilerplate
18. 18 What are AAC framework? • Libraries • Guidelines • Common scenarios in apps dev • Aims: ◦ Reduce boilerplate ◦ Reduce repetitive code
19. 19 What are AAC framework? • Libraries • Guidelines • Common scenarios in apps dev • Aims: ◦ Reduce boilerplate ◦ Reduce repetitive code ◦ Focus on core features
20. 20 Basic blocks of AAC
21. 21 Basic blocks of AAC • Room
22. 22 Basic blocks of AAC • Room → A SQLite object mapper (ORMLite - GreenDao)
23. 23 Basic blocks of AAC • Room → A SQLite object mapper (ORMLite - GreenDao) • LiveData
24. 24 Basic blocks of AAC • Room → A SQLite object mapper (ORMLite - GreenDao) • LiveData → A Lifecycle aware observable core component.
25. 25 Basic blocks of AAC • Room → A SQLite object mapper (ORMLite - GreenDao) • LiveData → A Lifecycle aware observable core component. • ViewModel
26. 26 Basic blocks of AAC • Room → A SQLite object mapper (ORMLite - GreenDao) • LiveData → A Lifecycle aware observable core component. • ViewModel → The communication points with the rest of the application for Activities / Fragments. They are UI code free and outlive the activity or fragment.
27. 27 Basic blocks of AAC • Room → A SQLite object mapper (ORMLite - GreenDao) • LiveData → A Lifecycle aware observable core component. • ViewModel → The communication points with the rest of the application for Activities / Fragments. They are UI code free and outlive the activity or fragment. • Lifecycle
28. 28 Basic blocks of AAC • Room → A SQLite object mapper (ORMLite - GreenDao) • LiveData → A Lifecycle aware observable core component. • ViewModel → The communication points with the rest of the application for Activities / Fragments. They are UI code free and outlive the activity or fragment. • Lifecycle → contains information about the lifecycle state of a component (for instance an Activity).
29. 29 Basic blocks of AAC • Room → A SQLite object mapper (ORMLite - GreenDao) • LiveData → A Lifecycle aware observable core component. • ViewModel → The communication points with the rest of the application for Activities / Fragments. They are UI code free and outlive the activity or fragment. • Lifecycle → contains information about the lifecycle state of a component (for instance an Activity). • Lifecycle owner
30. 30 Basic blocks of AAC • Room → A SQLite object mapper (ORMLite - GreenDao) • LiveData → A Lifecycle aware observable core component. • ViewModel → The communication points with the rest of the application for Activities / Fragments. They are UI code free and outlive the activity or fragment. • Lifecycle → contains information about the lifecycle state of a component (for instance an Activity). • Lifecycle owner → Interface - Annotations @OnLifecycleEvent(Lifecycle.Event.ON_START)
31. 31 Basic blocks of AAC • Room → A SQLite object mapper (ORMLite - GreenDao) • LiveData → A Lifecycle aware observable core component. • ViewModel → The communication points with the rest of the application for Activities / Fragments. They are UI code free and outlive the activity or fragment. • Lifecycle → contains information about the lifecycle state of a component (for instance an Activity). • Lifecycle owner → Interface - Annotations @OnLifecycleEvent(Lifecycle.Event.ON_START) • Lifecycle observer
32. 32 Basic blocks of AAC • Room → A SQLite object mapper (ORMLite - GreenDao) • LiveData → A Lifecycle aware observable core component. • ViewModel → The communication points with the rest of the application for Activities / Fragments. They are UI code free and outlive the activity or fragment. • Lifecycle → contains information about the lifecycle state of a component (for instance an Activity). • Lifecycle owner → Interface - Annotations @OnLifecycleEvent(Lifecycle.Event.ON_START) • Lifecycle observer → Interface - getLifecycle(): LifeCycleRegistry
33. Android Architecture Components - AAC Can be used in isolation. Work really well when used together, though.
34. 34 Using Architecture Components
35. 35 Using Architecture Components • App → Events Scheduler
36. 36 Using Architecture Components • App → Events Scheduler ◦ Event addition
37. 37 Using Architecture Components • App → Events Scheduler ◦ Event addition ◦ Event list
38. 38 Using Architecture Components • App → Events Scheduler ◦ Event addition ◦ Event list • Initial Version → Offline
39. 39 Using Architecture Components • App → Events Scheduler ◦ Event addition ◦ Event list • Initial Version → Offline • Architecture Components: ◦ Lifecycle ◦ ViewModel ◦ Room
40. 40 MVVM using Architecture Components EventRepository EventDatabase EventDao Events Event List EventListActivity EventListViewModel Add Event AddEventActivity AddEventViewModel extends ViewModel @Database (Room) @Dao (Room) extends Lifecycle
41. 41 What is Room? • New way to create databases in Android • ORM between Java and SQLite • Less verbose • No more Cursors • No more Loaders • Room isn’t a fully-fledged ORM (no complex nesting objects)
42. 42 How to query data?
43. 43 How to query data? • Using LiveData → exposes a stream of events that we can subscribe to receive updates for asynchronously
44. 44 How to query data? • Using LiveData → exposes a stream of events that we can subscribe to receive updates for asynchronously • Using RxJava2 (Flowable)
45. 45 How to query data? • Using LiveData → exposes a stream of events that we can subscribe to receive updates for asynchronously • Using RxJava2 (Flowable) • Place synchronous calls in a background thread such as an AsyncTask. (Room doesn’t allow to issue database queries on the main thread → ANRs)
46. 46 Looking at ViewModels • ViewModel name comes from MVVM pattern • Responsible for preparing data for the view • Expose data to any view listening for changes • Retain state across activity changes → No onSaveInstanceState() • Share data across activities/fragments → No actions • Stay in memory until Lifecycle is scoped ◦ Activity finishes / Fragment detached • Should not reference any View → Memory leak • Extend AndroidViewModel to access app context
47. 47 ViewModel’s Lifecycle
48. 48 How to work with AAC? • Empty Activity project • Add Google Maven Repo en project’s build.gradle • Add AAC’s components to app/build.gradle • Let’s code! :)
49. 49 References • Android Architecture Components - https://developer.android.com/topic/libraries/architecture/index.html • Android Lifecycles - https://developer.android.com/topic/libraries/architecture/lifecycle.html • Room Reference - https://developer.android.com/topic/libraries/architecture/room.html • LiveData Reference - https://developer.android.com/topic/libraries/architecture/livedata.html • ViewModel Reference - https://developer.android.com/topic/libraries/architecture/viewmodel.html
50. 50 References • Android Persistence Codelab - https://codelabs.developers.google.com/codelabs/android-persistence/#0 • Google’s Android Architecture Github - https://github.com/googlesamples/android-architecture • Project shown in this MeetUp session - cdmunoz - https://github.com/cdmunoz/EventSchedulerArchComp • Simple GoogleBooks MVVM project - cdmunoz - https://github.com/cdmunoz/GBooksViewModel
51. 51 QUESTIONS?