Android App Architecture & Navigation

A look into the new navigation architecture component and how it fits with Fragments and Activites

Transcript

1. Android App Architecture & Navigation Bryan Herbst (@bryancherbst)
2. Activities & Fragments
3. STOP
4. STOP If you like what you have, keep it
5. When to use what?
6. Where we’ve been
7. In the beginning there was Activity
8. Activity Entry point to your application
9. Activity Entry point to your application Has a Window
10. Activity Entry point to your application Has a Window Has a lifecycle
11. Activity Entry point to your application Has a Window Has a lifecycle Responds to configuration changes
12. Activity Entry point to your application Has a Window Has a lifecycle Responds to configuration changes ActivityManager handles back stack
13. Activity Layout inflation View manipulation Click handlers Animations Navigation Menu creation Menu item callbacks Database calls Networking calls Disk I/O Sensor input Geolocation
14. Activity Window transitions can be difficult !
15. Activity Window transitions can be difficult A lot of plumbing !
16. Activity Window transitions can be difficult A lot of plumbing Nuanced (and limited) backstack !
17. Enter Honeycomb (3.0)
19. Fragments!
20. Fragment Has lifecycle (less than Activity)
21. Fragment Has lifecycle (less than Activity) Backstack via FragmentManager
22. Fragment Has lifecycle (less than Activity) Backstack via FragmentManager Composable
23. Fragment Has lifecycle (less than Activity) Backstack via FragmentManager Composable Belong to an Activity
24. Fragments Transactions are annoying !
25. Fragments Transactions are annoying Lifecycles are annoying !
26. Fragments Transactions are annoying Lifecycles are annoying Can still be too big !
27. Fragments Transactions are annoying Lifecycles are annoying Can still be too big Bugs !
28. Fragments Transactions are annoying Lifecycles are annoying Can still be too big Bugs Differences from Activity !
29. Meanwhile
30. View-based architecture
31. View Draws things Reacts to user interaction
32. View Almost no lifecycle No backstack !
33. Where are we now?
34. Single activity app Easier to manage transitions
35. Single activity app Easier to manage transitions Composable UI elements
36. Single activity app Easier to manage transitions Composable UI elements Google can be opinionated
37. Don’t like lifecyles? Use Lifecycle
38. class MainActivity : Activity { override fun onStart() { super.onStart() analytics.reportStart() } }
39. activity.lifecycle .addObserver(AnalyticsObserver()) class AnalyticsObserver : LifecycleObserver { @OnLifecycleEvent(ON_START) fun trackPageLoad() { analytics.reportStart() } }
40. activity.lifecycle .addObserver(AnalyticsObserver()) class AnalyticsObserver : LifecycleObserver { @OnLifecycleEvent(ON_START) fun trackPageLoad() { analytics.reportStart() } }
41. Fragment refresher
42. Which Fragments? Framework fragments Support fragments
43. Which Fragments? Framework fragments Support fragments ! "
44. Fragment transactions
45. Fragment transactions fragmentManager.beginTransaction()
46. Fragment transactions fragmentManager.beginTransaction() .add()
47. Fragment transactions fragmentManager.beginTransaction() .remove()
48. Fragment transactions fragmentManager.beginTransaction() .replace()
49. Fragment transactions fragmentManager.beginTransaction() .show()
50. Fragment transactions fragmentManager.beginTransaction() .hide()
51. Fragment transactions fragmentManager.beginTransaction() .addToBackstack()
52. Fragment transactions fragmentManager.beginTransaction() .commit()
53. Fragment transactions fragmentManager.beginTransaction() .add() .replace() .hide() .addToBackstack() .commit()
54. Transactions are asynchronous
55. The IllegalStateException com.awesomeapp E/MainActivity: java.lang.IllegalStateException: Cannot perform this action after onSaveInstanceState
56. The IllegalStateException FM State
57. The IllegalStateException FM State add()
58. The IllegalStateException FM State add()
59. The IllegalStateException FM State add() hide()
60. The IllegalStateException FM State add() hide() onStop()!!
61. The IllegalStateException FM State add() hide() onStop()!! Persisted add() hide()
62. The IllegalStateException FM State onStart() Persisted add() hide()
63. The IllegalStateException FM State add() hide() Persisted add() hide() replace()
64. The IllegalStateException After onSaveInstanceState any future changes may be lost
65. Okay, but async transactions suck
66. Commit() commit() executePendingTransactions() commitAllowingStateLoss() commitNow() commitNowAllowingStateLoss()
67. Commit() commit() executePendingTransactions() commitAllowingStateLoss() commitNow() commitNowAllowingStateLoss()
68. Commit() commit() executePendingTransactions() commitAllowingStateLoss() commitNow() commitNowAllowingStateLoss()
69. Commit() commit() executePendingTransactions() commitAllowingStateLoss() commitNow() commitNowAllowingStateLoss()
70. Back stack addToBackStack(null)
71. Back stack popBackStack()
72. Back stack addToBackStack("screenA")
73. Back stack addToBackStack("screenA")
74. Back stack addToBackStack("screenB")
75. Back stack addToBackStack("screenC")
76. Back stack popBackStack("screenA", 0)
77. But that’s a lot of work
78. Navigation
79. Navigation Challenges Transitions
80. Navigation Challenges Transitions Back stack management
81. Navigation Challenges Transitions Back stack management Up vs. back
82. Navigation Challenges Transitions Back stack management Up vs. back Passing data
83. Navigation Challenges Transitions Back stack management Up vs. back Passing data Deep linking
84. Android Jetpack: Navigation
85. Principles Navigation is a stack
86. Principles Navigation is a stack Up never exits the app
87. Principles Navigation is a stack Up never exits the app Up = Back within your app
88. Principles Navigation is a stack Up never exits the app Up = Back within your app Deep linking should yield the same stack
89. Navigation (the library)
90. Navigation library No more Fragment transactions!
91. Navigation library No more Fragment transactions! No more startActivity()!
92. Navigation library No more Fragment transactions! No more startActivity()! Just call navigate()
93. Navigation Graph All the destinations in your app, plus the action that connect them.
94. Navigation Graph New XML resource type!
95. Navigation tooling
96. Navigator What destination types are available?
97. NavHost Where do those destinations reside?
98. NavController How do I get there?
99. Current Navigators ActivityNavigator
100. Current Navigators ActivityNavigator FragmentNavigator
101. <fragment android:id="@+id/navHost" android:name= "androidx.navigation.fragment.NavHostFragment" android:layout_width="match_parent" android:layout_height="match_parent" app:defaultNavHost="true" app:navGraph="@navigation/nav_graph" />
102. <fragment android:id="@+id/navHost" android:name= "androidx.navigation.fragment.NavHostFragment" android:layout_width="match_parent" android:layout_height="match_parent" app:defaultNavHost="true" app:navGraph="@navigation/nav_graph" />
103. Do the navigation Navigation .findNavController(view) .navigate(R.id.action_id)
104. Destinations: Deep link Destinations can have deep links <fragment android:id="@+id/home” android:name="com.example.HomeFragment" android:label="fragment_home"> <deepLink app:uri="http://example.com/detail"/> </fragment>
105. Actions: Animations Actions can have transition animations <action android:id="@+id/action_home_to_detail" app:destination="@id/detail" app:popEnterAnim="@anim/slide_in_left" app:popExitAnim="@anim/slide_out_right" app:enterAnim="@anim/slide_in_right" app:exitAnim="@anim/slide_out_left"/>
106. Actions: back stack Each action can define its own behavior <action android:id="@+id/home_to_details" app:destination="@id/details” app:popUpTo="@id/splash” app:popUpToInclusive="false" />
107. Arguments Actions can all have arguments <fragment> <argument android:name="name" android:defaultValue="Joe" /> </fragment>
108. Arguments Works with deep links! <fragment> <argument android:name="name" android:defaultValue="Joe" /> <deepLink app:uri="example.com/{name}" /> </fragment>
109. Safeargs androidx.navigation.safeargs
110. Safeargs androidx.navigation.safeargs Generates argument wrapper classes
111. Safeargs Demo time!
112. Demo time!
113. Custom destination You can make your own Navigator!
114. What’s missing Some integration with common elements like bottom navigation
115. What’s missing Some integration with common elements like bottom navigation Shared element transitions
116. What’s missing Some integration with common elements like bottom navigation Shared element transitions Nested navigation graphs
117. What’s missing Some integration with common elements like bottom navigation Shared element transitions Nested navigation graphs Result data (e.g. startActivityForResult())
118. What if I want to migrate to Navigation?
119. I currently have…
120. Single Activity
121. Single Activity Set up navigation graph
122. Single Activity Set up navigation graph Each Fragment is a destination
123. Single Activity Set up navigation graph Each Fragment is a destination Every transaction is an action
124. Single Activity Set up navigation graph Each Fragment is a destination Every transaction is an action Define arguments
125. Single Activity Set up navigation graph Each Fragment is a destination Every transaction is an action Define arguments Replace transactions with NavController.navigate()
126. Multiple activities Start by making a graph for each Activity
127. Multiple activities Start by making a graph for each Activity If you want a single Activity, combine Activities one screen at a time
128. Activity Chrome
129. Activity Chrome CoordinatorLayout .setStatusBarBackgroundColor()
130. Activity Features <activity android:name=".MainActivity" android:windowSoftInputMode="adjustPan" />
131. Activity Features <activity android:name=".MainActivity" android:windowSoftInputMode="adjustPan" /> activity.window .setSoftInputMode(SOFT_INPUT_ADJUST_PAN)
132. More complex Watch for updates! Provide feedback!
133. Resources https://developer.android.com /topic /libraries /architecture /navigation