Secrets of Android Jetpack

In recent years, Android Jetpack has been developing at an incredible pace and keeping track of all the new products is not easy. The report will provide an overview of the latest API and the future of their AndroidX, which are changing the approach to developing Android apps.

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1. SECRETS OF ANDROID JETPACK KIRILL ROZOV / REPLIKA.AI
2. • Activity • Fragment • Core • ViewModel • LiveData • Navigation AGENDA 2
3. • Develop Android apps for 8+ years • Kotlin Lover • Mobile Lead at Replika.ai • Author of “Android Broadcast” Project • Cohost of Android Dev Virtual Meetups • Cohost of Mobile People Talks podcast WHO AM I? KIRILL ROZOV @kirill_rozov @krlrozov
5. ACTIVITY
6. class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) } } CONTENT VIEW 6
7. class MainActivity : AppCompatActivity(R.layout.activity_main) CONTENT VIEW 7
8. class MainActivity : AppCompatActivity() { var pictureUri: Uri? = null fun onPictureTaken(uri: Uri?, isImageSaved: Boolean) { "# Process the image } fun takePicture() { val pictureUri: Uri = Uri.fromFile(File.createTempFile("androidx-secrets", System.currentTimeMillis().toString())) this.pictureUri = pictureUri val intent = Intent(MediaStore.ACTION_IMAGE_CAPTURE).putExtra(MediaStore.EXTRA_OUTPUT, pictureUri) startActivityForResult(intent, REQUEST_CODE_TAKE_PHOTO) } override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) { if (requestCode "$ REQUEST_CODE_TAKE_PHOTO) { onPictureTaken(pictureUri, resultCode "$ Activity.RESULT_OK) } else { super.onActivityResult(requestCode, resultCode, data) } } companion object { const val REQUEST_CODE_TAKE_PHOTO = 1 } } ACTIVITY RESULT 8
9. class MainActivity : AppCompatActivity() { var pictureUri: Uri? = null val takePhoto = registerForActivityResult(TakePicture()) { isImageSaved "# onPictureTaken(pictureUri, isImageSaved) this.pictureUri = null } fun onPictureTaken(uri: Uri?, isImageSaved: Boolean) { "# Process the image } fun takePicture() { val pictureUri = Uri.fromFile(File.createTempFile("androidx-secrets", System.currentTimeMillis().toString())) this.pictureUri = pictureUri takePhoto.launch(pictureUri) } ACTIVITY RESULT API 9
10. class TakePicture : ActivityResultContract<Uri, Boolean>() { override fun createIntent(context: Context, input: Uri): Intent { return Intent(MediaStore.ACTION_IMAGE_CAPTURE) .putExtra(MediaStore.EXTRA_OUTPUT, input) } override fun getSynchronousResult( context: Context, input: Uri ): SynchronousResult<Boolean>? { return null } override fun parseResult(resultCode: Int, intent: Intent?): Boolean { return resultCode "$ Activity.RESULT_OK } } ACTIVITY RESULT API 10
11. • CreateDocument • OpenDocument • OpenDocumentTree • OpenMultipleDocuments • GetContent • GetMultipleContent • PickContact • StartActivityForResult • StartIntentSenderForResult • TakePicture • TakePicturePreview • TakeVideo • RequestPermission • RequestMultiplePermissions PREDEFINED CONTRACTS 11
12. class MainActivity : AppCompatActivity() { val requestPermissionForTrackUserResult = registerForActivityResult(RequestPermission()) { permissionGranted "# if (permissionGranted) { trackUser() } } @RequiresPermission(Manifest.permission.ACCESS_FINE_LOCATION) fun trackUser() { "# Start track user } fun requestPermissionForTrackUser() { requestPermissionForTrackUserResult.launch(Manifest.permission.ACCESS_FINE_LOCATION) } } ACTIVITY RESULT API FOR PERMISSIONS 12
13. FRAGMENT
14. class MainFragment : Fragment() { override fun onCreateView( inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle? ): View? { return inflater.inflate(R.layout.fragment_main, container, false) } } FRAGMENT’S VIEW 14
15. class MainFragment : Fragment(R.layout.fragment_main) FRAGMENT’S VIEW 15
16. • Callback via parent Fragment/Activity • Target Fragment • Shared View Model SHARE RESULT BETWEEN FRAGMENTS 16
17. class FromFragment : Fragment() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) childFragmentManager.setFragmentResultListener( EndFragment.REQUEST_KEY, this ) { requestKey: String, result: Bundle "# val isSuccess = result.getBoolean(EndFragment.KEY_SUCCESS) "# Do something with the result"% } } fun startFragment() { childFragmentManager.commit { add(android.R.id.content, EndFragment(), FRAGMENT_END) } } } FRAGMENT RESULT API 17
18. class EndFragment : Fragment() { fun updateResult(success: Boolean) { val result = bundleOf(KEY_SUCCESS to success) parentFragmentManager.setFragmentResult(REQUEST_KEY, result) } } FRAGMENT RESULT API 18
19. class MainFragment : Fragment() { @Inject lateinit var deps: Deps } DI IN FRAGMENT 19
20. class MainFragment : Fragment() { @Inject private lateinit var deps: Deps } DI IN FRAGMENT 20
21. class MainFragment : Fragment() { @Inject private var deps: Deps } DI IN FRAGMENT 21
22. class MainFragment : Fragment() { @Inject private val deps: Deps } DI IN FRAGMENT 22
23. class MainFragment @Inject constructor( private val deps: Deps ) : Fragment() DI IN FRAGMENT 23
24. class FragmentFactory { open fun instantiate( classLoader: ClassLoader, className: String ): Fragment } FRAGMENT FACTORY 24
25. class InjectFragmentFactory( providers: Map<Class<out Fragment>, Provider<Fragment"& ) : FragmentFactory() { private val providers = providers.mapKeys { (fragmentClass, _) "# fragmentClass.name } override fun instantiate( classLoader: ClassLoader, className: String ): Fragment { return providers[className]"'get() "( super.instantiate(classLoader, className) } } FRAGMENT FACTORY 25
26. "# Set the fragmentFactory as default for every FragmentActivity in the app class SetFragmentFactory( private val fragmentFactory: FragmentFactory ) : Application.ActivityLifecycleCallbacks { override fun onActivityCreated( activity: Activity, savedInstanceState: Bundle? ) { if (activity is FragmentActivity) { activity.supportFragmentManager.fragmentFactory = this.fragmentFactory } } } FRAGMENT FACTORY 26
27. • Injection in Fragment constructor • No more Component.inject(*Fragment) • Less re lection/more performance • Possibility to obfuscate Fragments FRAGMENT FACTORY BONUSES 27
28. fragmentManager.commit { add(android.R.id.content, NextFragment(), FRAGMENT_TAG) } FRAGMENT TRANSCATION 28
29. fragmentManager.commit { add( android.R.id.content, fragmentClass = NextFragment")class.java, args = null, tag = FRAGMENT_TAG ) } FRAGMENT TRANSCATION 29
30. fragmentManager.commit { add<NextFragment>( android.R.id.content, args = null, tag = FRAGMENT_TAG ) } FRAGMENT TRANSCATION 30
31. ANDROIDX CORE
32. val builder = SpannableStringBuilder() builder.append("Hello") builder.setSpan( StyleSpan(Typeface.ITALIC), 0, builder.length, SPAN_INCLUSIVE_EXCLUSIVE ) builder.append(",") val start = builder.length builder.append("World!") builder.setSpan( StyleSpan(Typeface.BOLD), start, builder.length, SPAN_INCLUSIVE_EXCLUSIVE ) BUILD SPANNED STRING 33
33. buildSpannedString { italic { append("Hello") } append(",") bold { append("World!") } } BUILD SPANNED STRING 34
34. val activityManager = context.getSystemService(Context.ACTIVITY_SERVICE) val activityManager = context.getSystemService() SYSTEM SERVICES 35
35. val activityManager: Any? = context.getSystemService(Context.ACTIVITY_SERVICE) val activityManager: ActivityManager? = context.getSystemService() SYSTEM SERVICES 36
36. val attrs = context.obtainStyledAttributes( attributes, R.styleable.CustomView, defStyleAttr, 0 ) main = attrs.getBoolean(R.styleable.CustomView_main, false) attrs.recycle() CUSTOM VIEW ATTRIBUTES 37
37. context.withStyledAttributes( set = attributes, attrs = R.styleable.CustomView, defStyleAttr = defStyleAttr ) { main = attrs.getBoolean(R.styleable.CustomView_main, false) } CUSTOM VIEW ATTRIBUTES 38
38. fun makeArgs(): Bundle { val args = Bundle() args.putString(KEY1, "value") args.putInt(KEY2, 1) return args } BUNDLE 39
39. fun makeArgs(): Bundle { return Bundle().apply { putString(KEY1, "value") putInt(KEY2, 1) } } BUNDLE 40
40. fun makeArgs(): Bundle { return Bundle(2).apply { putString(KEY1, "value") putInt(KEY2, 1) } } BUNDLE 41
41. fun makeArgs(): Bundle { return bundleOf(KEY1 to "value", KEY2 to 1) } BUNDLE 42
42. fun bundleOf(vararg pairs: Pair<String, Any?>) = Bundle(pairs.size).apply { for ((key, value) in pairs) { when (value) { null "* putString(key, null) is Boolean "* putBoolean(key, value) is Byte "* putByte(key, value) is Char "* putChar(key, value) is Double "* putDouble(key, value) is Float "* putFloat(key, value) is Int "* putInt(key, value) is Long "* putLong(key, value) is Short "* putShort(key, value) … } } } ⚠ UNDER THE HOOD 43
43. LIFECYCLE
44. class MainFragment : Fragment() { private val viewModel: MainViewModel = ViewModelProvider( this, MainViewModel.Factory() ).get(MainViewModel")class.java) } VIEW MODEL CREATION 45
45. class MainFragment : Fragment() { private val viewModel: MainViewModel by viewModels { MainViewModel.Factory() } } VIEW MODEL CREATION 46
46. class MainFragment @Inject constructor( private val viewModelFactory: Provider<MainViewModel.Factory> ) : Fragment() { private val viewModel: MainViewModel by viewModels { viewModelFactory.get() } } VIEW MODEL CREATION 47
47. VIEWMODEL. SAVING STATE 48
48. "# androidx.lifecycle:lifecycle-viewmodel-savedstate"+version> class MainViewModel(savedStateHandle: SavedStateHandle) : ViewModel() { val text: MutableLiveData<String> = savedStateHandle.getLiveData(STATE_TEXT) } VIEW MODEL. SAVING STATE 49
49. class MainViewModel(private val githubService: GithubService) : ViewModel() { val users: LiveData<List<User"& = liveData { while (true) { var delayDuration = 5_000L "# Ms try { emit(githubService.fetchUsers()) break } catch (e: Exception) { delay(delayDuration) delayDuration *= 2 } } } } LIVEDATA BUILDER + COROUTINE 50
50. NAVIGATION
51. <navigation app:startDestination=“@id/home_fragment" > <fragment android:id="@+id/home_fragment" android:name=“HomeViewPagerFragment > <action android:id="@+id/action_home_to_plant_detail" app:destination=“@id/plant_detail_fragment" ", "-fragment> <fragment android:id="@+id/plant_detail_fragment" android:name="PlantDetailFragment" android:label=“@string/plant_detail_title" > <argument android:name=“plantId" app:argType=“string" ", "-fragment> "-navigation> NAVIGATION GRAPH. XML 52
52. navHostFragment.navController.apply { graph = createGraph(AppNavGraph.id, AppNavGraph.Dest.home) { fragment<HomeViewPagerFragment>(AppNavGraph.Dest.home) { label = getString(R.string.home_title) action(AppNavGraph.Action.toPlantDetail) { destinationId = AppNavGraph.Dest.plantDetail } } fragment<PlantDetailFragment>(AppNavGraph.Dest.plantDetail) { label = getString(R.string.plant_detail_title) argument(AppNavGraph.Args.plantId) { type = NavType.StringType } } } } NAVIGATION GRAPH. KOTLIN DSL 53 object AppNavGraph { const val id = 1 object Dest { const val home = 2 const val plantDetail = 3 } object Action { const val toPlantDetail = 4 } object Args { const val plantId = "plantId" } }
53. • No preview • All ids by your hands • No “safe args” plugins NAVIGATION GRAPH. KOTLIN DSL 54
54. • Hilt for Dagger 2 (Alpha) • Paging 3.0 (Alpha) • Benchmark • Startup (Alpha) • CameraX (Beta) • AsyncLayoutIn later • Constraint Layout 2.0 (Beta) • MotionLayout (Beta) • Vector Drawable • SavedState • Exif Interface • RecyclerView • and many more… MORE JETPACK LIBRARIES 55
55. THANKS YOU! QUESTIONS TIME KIRILL ROZOV / REPLIKA.AI @kirill_rozov @krlrozov youtube.com/c/androidbroadcast