The A, B and C of Lifecycle Components

[Droidcon Berlin '18] If you've been developing Android applications for a while now, you know the pain of handling the lifecycle just right. It’s a pain-point that has existed since the advent of Android, up until recently when Google released Architecture components. As an Android developer you are bugged by handling activity/fragment lifecycle and flow of data in tandem to the lifecycle changes day in and out. Making your code aware about the lifecycle of the process/activity/fragment makes you more confident as a developer and enables faster development. This session would enable you to understand Lifecycle components (ProcessLifecycleOwner, LifecycleOwner, LifecycleObserver) and how they are leveraged in other architecture components like LiveData and ViewModel.

Google Slides Link: https://docs.google.com/presentation/d/1b8mEH9hwwBxUiUk4xxib15sL7UIAYrP2TiSDXY9ZGS4

Transcript

1. Nishant Srivastava The A,B and C of Lifecycle Components
2. Nishant Srivastava twitter.com/nisrulz github.com/nisrulz www.nisrulz.com
3. Soundbrenner
4. The Challenge @nisrulz #DCBERLIN18
5. The Challenge Android activity lifecycle.. @nisrulz #DCBERLIN18
6. The Challenge Android activity lifecycle @nisrulz #DCBERLIN18
7. The Challenge Android activity lifecycle - Many states @nisrulz #DCBERLIN18
8. The Challenge Android activity lifecycle - Many states - Repeats on configuration changes @nisrulz #DCBERLIN18
9. The Challenge Android activity lifecycle - Many states - Repeats on configuration changes Not to forget... @nisrulz #DCBERLIN18
10. The Challenge ...the Fragment lifecycle. @nisrulz #DCBERLIN18
11. The Challenge ...the Fragment lifecycle. @nisrulz #DCBERLIN18
12. Architecture Components @nisrulz #DCBERLIN18
13. Lifecycle Components @nisrulz #DCBERLIN18
14. Lifecycle Components Series of classes designed to help deal with lifecycles in a more consistent fashion. @nisrulz #DCBERLIN18
15. Lifecycle Components Series of classes designed to help deal with lifecycles in a more consistent fashion. - Lifecycle - LifecycleOwner - LifecycleObserver @nisrulz #DCBERLIN18
16. Lifecycle @nisrulz #DCBERLIN18
17. Lifecycle Series of states an object can be in. For Android: Object that defines Android lifecycle states. i.e. Activity & Fragment @nisrulz #DCBERLIN18
18. Lifecycle @nisrulz #DCBERLIN18
19. Lifecycle dependencies { def lifecycle_version = "1.1.1" // Support library already depends on this (since v26.1.0) // Both AppCompatActivity & Support Fragment implement // LifecycleOwner interface. // Lifecycles only implementation "android.arch.lifecycle:runtime:$lifecycle_version" ... } @nisrulz #DCBERLIN18
20. Lifecycle // Source code public abstract class Lifecycle { // Adds a LifecycleObserver addObserver(@NonNull LifecycleObserver observer) // Removes the given observer from the observers list removeObserver(@NonNull LifecycleObserver observer) // Current state of the Lifecycle getCurrentState() // Compares the lifecycle states isAtLeast(@NonNull State state) ... } @nisrulz #DCBERLIN18
21. Lifecycle // Source code public abstract class Lifecycle { // Adds a LifecycleObserver addObserver(@NonNull LifecycleObserver observer) // Removes the given observer from the observers list removeObserver(@NonNull LifecycleObserver observer) // Current state of the Lifecycle getCurrentState() // Compares the lifecycle states isAtLeast(@NonNull State state) ... } @nisrulz #DCBERLIN18
22. Lifecycle // Source code public abstract class Lifecycle { // Adds a LifecycleObserver addObserver(@NonNull LifecycleObserver observer) // Removes the given observer from the observers list removeObserver(@NonNull LifecycleObserver observer) // Current state of the Lifecycle getCurrentState() // Compares the lifecycle states isAtLeast(@NonNull State state) ... } @nisrulz #DCBERLIN18
23. LifecycleOwner @nisrulz #DCBERLIN18
24. LifecycleOwner Interface that goes through Android Lifecycle. @nisrulz #DCBERLIN18
25. LifecycleOwner Interface that goes through Android Lifecycle. // Source code public interface LifecycleOwner { // Returns the Lifecycle of the provider. @NonNull Lifecycle getLifecycle(); } @nisrulz #DCBERLIN18
26. LifecycleOwner class MainActivity : AppCompatActivity() { // Missing myLifecycleObserver override fun onResume() { // Add lifecycle observer lifecycle.addObserver(myLifecycleObserver) } override fun onStop() { // Remove lifecycle observer lifecycle.removeObserver(myLifecycleObserver) } } @nisrulz #DCBERLIN18
27. LifecycleOwner Fun Fact: Activities & fragments are not the only things with lifecycle by default @nisrulz #DCBERLIN18
28. LifecycleOwner Fun Fact: Activities & fragments are not the only things with lifecycle by default You also have - LifecycleService - ProcessLifecycleOwner @nisrulz #DCBERLIN18
29. LifecycleService @nisrulz #DCBERLIN18
30. LifecycleService A service that is also a LifecycleOwner @nisrulz #DCBERLIN18
31. LifecycleService A service that is also a LifecycleOwner // Source code public class LifecycleService extends Service implements LifecycleOwner { ... } @nisrulz #DCBERLIN18
32. ProcessLifecycleOwner @nisrulz #DCBERLIN18
33. ProcessLifecycleOwner - Class that tracks the lifecycle of @nisrulz #DCBERLIN18
34. ProcessLifecycleOwner - Class that tracks the lifecycle of - whole application process or - all the activities combined @nisrulz #DCBERLIN18
35. ProcessLifecycleOwner - Class that tracks the lifecycle of - whole application process or - all the activities combined - Useful for reacting to app coming to foreground or going to background @nisrulz #DCBERLIN18
36. ProcessLifecycleOwner dependencies { def lifecycle_version = "1.1.1" // For ProcessLifecycleOwner implementation "android.arch.lifecycle:extensions:$lifecycle_version" ... } @nisrulz #DCBERLIN18
37. ProcessLifecycleOwner ON_CREATE ON_START & ON_RESUME ON_PAUSE & ON_STOP ON_DESTROY @nisrulz #DCBERLIN18
38. ProcessLifecycleOwner ON_CREATE (Only 1 time) ON_START & ON_RESUME ON_PAUSE & ON_STOP ON_DESTROY @nisrulz #DCBERLIN18
39. ProcessLifecycleOwner ON_CREATE (Only 1 time) ON_START & ON_RESUME (First Activity pass) ON_PAUSE & ON_STOP ON_DESTROY @nisrulz #DCBERLIN18
40. ProcessLifecycleOwner ON_CREATE (Only 1 time) ON_START & ON_RESUME (First Activity pass) ON_PAUSE & ON_STOP (after 700ms delay) ON_DESTROY @nisrulz #DCBERLIN18
41. ProcessLifecycleOwner ON_CREATE (Only 1 time) ON_START & ON_RESUME (First Activity pass) ON_PAUSE & ON_STOP (after 700ms delay) ON_DESTROY @nisrulz #DCBERLIN18
42. ProcessLifecycleOwner ON_CREATE (Only 1 time) ON_START & ON_RESUME (First Activity pass) ON_PAUSE & ON_STOP (after 700ms delay) ON_DESTROY @nisrulz #DCBERLIN18
43. ProcessLifecycleOwner ON_PAUSE & ON_STOP (after 700ms delay) @nisrulz #DCBERLIN18
44. ProcessLifecycleOwner ON_PAUSE & ON_STOP (after 700ms delay) // Source code public class ProcessLifecycleOwner implements LifecycleOwner { static final long TIMEOUT_MS = 700; //mls ... } @nisrulz #DCBERLIN18
45. ProcessLifecycleOwner Guarantee that ProcessLifecycleOwner won’t send any events if activities are - Destroyed - Recreated due to configuration change @nisrulz #DCBERLIN18
46. ProcessLifecycleOwner Comes with cost: @nisrulz #DCBERLIN18
47. ProcessLifecycleOwner Comes with cost: extension artifact automatically adds <provider> element to your manifest @nisrulz #DCBERLIN18
48. ProcessLifecycleOwner <manifest > <application> ... <provider android:name="android.arch.lifecycle.ProcessLifecycleOwnerInitializer" android:authorities="com.example.app.lifecycle-trojan" android:exported="false" android:multiprocess="true" /> </application> </manifest> @nisrulz #DCBERLIN18
49. ProcessLifecycleOwner // Source code // Internal class to initialize Lifecycles. public class ProcessLifecycleOwnerInitializer extends ContentProvider { @Override public boolean onCreate() { ... ProcessLifecycleOwner.init(getContext()); return true; } ... } @nisrulz #DCBERLIN18
50. ProcessLifecycleOwner Side-effect: @nisrulz #DCBERLIN18
51. ProcessLifecycleOwner Side-effect: Inits ProcessLifecycleOwner even if your app does not use it! @nisrulz #DCBERLIN18
52. ProcessLifecycleOwner Side-effect: Inits ProcessLifecycleOwner even if your app does not use it! Why? @nisrulz #DCBERLIN18
53. ProcessLifecycleOwner Side-effect: Inits ProcessLifecycleOwner even if your app does not use it! Why? So that ProcessLifecycleOwner can be invoked as soon as process starts @nisrulz #DCBERLIN18
54. @nisrulz #DCBERLIN18 Application.ActivityLifecycleCallback vs ProcessLifecycleOwner
55. @nisrulz #DCBERLIN18 Application.ActivityLifecycleCallback vs or ProcessLifecycleOwner
56. Application.ActivityLifecycleCallback // Source code public interface ActivityLifecycleCallbacks { void onActivityCreated(Activity var1, Bundle var2); ... void onActivitySaveInstanceState(Activity var1, Bundle var2); void onActivityDestroyed(Activity var1); } @nisrulz #DCBERLIN18
57. Application.ActivityLifecycleCallback // Register for the callback application .registerActivityLifecycleCallbacks(object: Application.ActivityLifecycleCallbacks{ override fun onActivityCreated(activity: Activity?, bundle: Bundle?) {} ... }) @nisrulz #DCBERLIN18
58. ProcessLifecycleOwner // Source code public class ProcessLifecycleOwner implements LifecycleOwner { ... void attach(Context context) { ... Application app = (Application) context.getApplicationContext(); app.registerActivityLifecycleCallbacks (new EmptyActivityLifecycleCallbacks() { @Override public void onActivityCreated(Activity activity, Bundle savedInstanceState) { .. } ... }); } } @nisrulz #DCBERLIN18
59. ProcessLifecycleOwner // Source code public class ProcessLifecycleOwner implements LifecycleOwner { ... void attach(Context context) { ... Application app = (Application) context.getApplicationContext(); app.registerActivityLifecycleCallbacks (new EmptyActivityLifecycleCallbacks() { @Override public void onActivityCreated(Activity activity, Bundle savedInstanceState) { .. } ... }); } } @nisrulz #DCBERLIN18
60. ProcessLifecycleOwner // Source code public class ProcessLifecycleOwner implements LifecycleOwner { ... void attach(Context context) { ... Application app = (Application) context.getApplicationContext(); app.registerActivityLifecycleCallbacks (new EmptyActivityLifecycleCallbacks() { @Override public void onActivityCreated(Activity activity, Bundle savedInstanceState) { .. } ... }); } } @nisrulz #DCBERLIN18
61. ProcessLifecycleOwner // Source code class EmptyActivityLifecycleCallbacks implements Application.ActivityLifecycleCallbacks { @Override public void onActivityCreated(Activity activity, Bundle savedInstanceState) { //Empty method body } ... } @nisrulz #DCBERLIN18
62. ProcessLifecycleOwner // Source code class EmptyActivityLifecycleCallbacks implements Application.ActivityLifecycleCallbacks { @Override public void onActivityCreated(Activity activity, Bundle savedInstanceState) { //Empty method body } ... } @nisrulz #DCBERLIN18
63. LifecycleRegistry @nisrulz #DCBERLIN18
64. LifecycleRegistry Implementation of Lifecycle that can handle multiple observers @nisrulz #DCBERLIN18
65. LifecycleRegistry Implementation of Lifecycle that can handle multiple observers // Source code public class LifecycleRegistry extends Lifecycle { ... } @nisrulz #DCBERLIN18
66. LifecycleRegistry Implementation of Lifecycle that can handle multiple observers // Source code public class LifecycleRegistry extends Lifecycle { ... } However, you need to dispatch the events yourself. @nisrulz #DCBERLIN18
67. LifecycleRegistry class MyLifecycleOwner : LifecycleOwner { private var registry: LifecycleRegistry = LifecycleRegistry(this) init { registry.handleLifecycleEvent(Lifecycle.Event.ON_CREATE) } override fun getLifecycle(): Lifecycle = registry fun startListening() { registry.handleLifecycleEvent(Lifecycle.Event.ON_START) } fun stopListening() { registry.handleLifecycleEvent(Lifecycle.Event.ON_STOP) } } @nisrulz #DCBERLIN18
68. LifecycleRegistry class MyLifecycleOwner : LifecycleOwner { private var registry: LifecycleRegistry = LifecycleRegistry(this) init { registry.handleLifecycleEvent(Lifecycle.Event.ON_CREATE) } override fun getLifecycle(): Lifecycle = registry fun startListening() { registry.handleLifecycleEvent(Lifecycle.Event.ON_START) } fun stopListening() { registry.handleLifecycleEvent(Lifecycle.Event.ON_STOP) } } @nisrulz #DCBERLIN18
69. LifecycleRegistry class MyLifecycleOwner : LifecycleOwner { private var registry: LifecycleRegistry = LifecycleRegistry(this) init { registry.handleLifecycleEvent(Lifecycle.Event.ON_CREATE) } override fun getLifecycle(): Lifecycle = registry fun startListening() { registry.handleLifecycleEvent(Lifecycle.Event.ON_START) } fun stopListening() { registry.handleLifecycleEvent(Lifecycle.Event.ON_STOP) } } @nisrulz #DCBERLIN18
70. LifecycleRegistry class MyLifecycleOwner : LifecycleOwner { private var registry: LifecycleRegistry = LifecycleRegistry(this) init { registry.handleLifecycleEvent(Lifecycle.Event.ON_CREATE) } override fun getLifecycle(): Lifecycle = registry fun startListening() { registry.handleLifecycleEvent(Lifecycle.Event.ON_START) } fun stopListening() { registry.handleLifecycleEvent(Lifecycle.Event.ON_STOP) } } @nisrulz #DCBERLIN18
71. LifecycleRegistry class MyLifecycleOwner : LifecycleOwner { private var registry: LifecycleRegistry = LifecycleRegistry(this) init { registry.handleLifecycleEvent(Lifecycle.Event.ON_CREATE) } override fun getLifecycle(): Lifecycle = registry fun startListening() { registry.handleLifecycleEvent(Lifecycle.Event.ON_START) } fun stopListening() { registry.handleLifecycleEvent(Lifecycle.Event.ON_STOP) } } @nisrulz #DCBERLIN18
72. LifecycleRegistry val myLifecycleOwner = MyLifecycleOwner() // Missing myLifecycleObserver // Add lifecycle observer myLifecycleOwner.lifecycle.addObserver(myLifecycleObserver) // Remove lifecycle observer myLifecycleOwner.lifecycle.removeObserver(myLifecycleObserver) @nisrulz #DCBERLIN18
73. LifecycleObserver @nisrulz #DCBERLIN18
74. LifecycleObserver An interface for observing a Lifecycle // Source code public interface LifecycleObserver { // Empty } @nisrulz #DCBERLIN18
75. LifecycleObserver Two ways to implement - Annotation - Callback Interface @nisrulz #DCBERLIN18
76. LifecycleObserver dependencies { def lifecycle_version = "1.1.1" // For Annotation Support annotationProcessor "android.arch.lifecycle:compiler:$lifecycle_version" ... } @nisrulz #DCBERLIN18
77. LifecycleObserver class MyLifecycleObserver : LifecycleObserver { @OnLifecycleEvent(Lifecycle.Event.ON_CREATE) fun init() {} @OnLifecycleEvent(Lifecycle.Event.ON_START) fun onStart() {} ... @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY) fun cleanup() {} } @nisrulz #DCBERLIN18
78. LifecycleObserver val myLifecycleOwner = MyLifecycleOwner() // Add lifecycle observer myLifecycleOwner.lifecycle.addObserver(myLifecycleObserver) // Remove lifecycle observer myLifecycleOwner.lifecycle.removeObserver(myLifecycleObserver) @nisrulz #DCBERLIN18
79. LifecycleObserver val myLifecycleOwner = MyLifecycleOwner() val myLifecycleObserver = MyLifecycleObserver() // Add lifecycle observer myLifecycleOwner.lifecycle.addObserver(myLifecycleObserver) // Remove lifecycle observer myLifecycleOwner.lifecycle.removeObserver(myLifecycleObserver) @nisrulz #DCBERLIN18
80. LifecycleObserver val myLifecycleOwner = MyLifecycleOwner() val myLifecycleObserver = MyLifecycleObserver() // Add lifecycle observer myLifecycleOwner.lifecycle.addObserver(myLifecycleObserver) // Remove lifecycle observer myLifecycleOwner.lifecycle.removeObserver(myLifecycleObserver) @nisrulz #DCBERLIN18
81. DefaultLifecycleObserver @nisrulz #DCBERLIN18
82. DefaultLifecycleObserver Callback interface for listening to LifecycleOwner state changes. @nisrulz #DCBERLIN18
83. DefaultLifecycleObserver Callback interface for listening to LifecycleOwner state changes. Recommended over annotations if using Java 8 language. @nisrulz #DCBERLIN18
84. DefaultLifecycleObserver android { compileOptions { sourceCompatibility JavaVersion.VERSION_1_8 targetCompatibility JavaVersion.VERSION_1_8 } } dependencies { def lifecycle_version = "1.1.1" // For DefaultLifecycleObserver implementation "android.arch.lifecycle:common-java8:$lifecycle_version" ... } @nisrulz #DCBERLIN18
85. DefaultLifecycleObserver // Source code public interface DefaultLifecycleObserver extends FullLifecycleObserver { @Override default void onCreate(@NonNull LifecycleOwner owner) { ... } ... @Override default void onDestroy(@NonNull LifecycleOwner owner) { ... } } @nisrulz #DCBERLIN18
86. DefaultLifecycleObserver // Source code interface FullLifecycleObserver extends LifecycleObserver { void onCreate(LifecycleOwner owner); void onStart(LifecycleOwner owner); ... void onDestroy(LifecycleOwner owner); } @nisrulz #DCBERLIN18
87. DefaultLifecycleObserver class MyLifecycleObserver : DefaultLifecycleObserver { override fun onCreate(owner: LifecycleOwner) {} ... override fun onDestroy(owner: LifecycleOwner) {} } @nisrulz #DCBERLIN18
88. LiveData @nisrulz #DCBERLIN18
89. LiveData A lifecycle aware base class for encapsulating loading data @nisrulz #DCBERLIN18
90. LiveData A lifecycle aware base class for encapsulating loading data Lightweight implementation of Observer pattern @nisrulz #DCBERLIN18
91. LiveData dependencies { def lifecycle_version = "1.1.1" // For LiveData implementation "android.arch.lifecycle:livedata:$lifecycle_version" ... } @nisrulz #DCBERLIN18
92. LiveData // Source Code public abstract class LiveData<T> { ... protected void postValue(T value) {...} ... @MainThread protected void setValue(T value) {...} ... protected void onActive() {...} protected void onInactive() {...} } @nisrulz #DCBERLIN18
93. LiveData // Source Code public abstract class LiveData<T> { ... protected void postValue(T value) {...} // Sets the value async ... @MainThread protected void setValue(T value) {...} ... protected void onActive() {...} protected void onInactive() {...} } @nisrulz #DCBERLIN18
94. LiveData // Source Code public abstract class LiveData<T> { ... protected void postValue(T value) {...} // Sets the value async ... @MainThread protected void setValue(T value) {...} // Sets the value sync ... protected void onActive() {...} protected void onInactive() {...} } @nisrulz #DCBERLIN18
95. LiveData // Source Code public abstract class LiveData<T> { ... protected void postValue(T value) {...} // Sets the value async ... @MainThread protected void setValue(T value) {...} // Sets the value sync ... protected void onActive() {...} // Has active observers i.e in Start/Resume state protected void onInactive() {...} } @nisrulz #DCBERLIN18
96. LiveData // Source Code public abstract class LiveData<T> { ... protected void postValue(T value) {...} // Sets the value async ... @MainThread protected void setValue(T value) {...} // Sets the value sync ... protected void onActive() {...} // Has active observers i.e in Start/Resume state protected void onInactive() {...} // Has 0 active observers } @nisrulz #DCBERLIN18
97. LiveData class MySensorLiveData(context: Context?) : LiveData<Float>() { val sensorManager: SensorManager? = context? .getSystemService(Service.SENSOR_SERVICE) as SensorManager val sensorListener: SensorEventListener = object : SensorEventListener { override fun onSensorChanged(event: SensorEvent?) { // Set Value setValue(event?.values?.get(0)) } ... } } @nisrulz #DCBERLIN18
98. LiveData class MySensorLiveData(context: Context?) : LiveData<Float>() { val sensorManager: SensorManager? = context? .getSystemService(Service.SENSOR_SERVICE) as SensorManager val sensorListener: SensorEventListener = object : SensorEventListener { override fun onSensorChanged(event: SensorEvent?) { // Set Value setValue(event?.values?.get(0)) } ... } } @nisrulz #DCBERLIN18
99. LiveData class MySensorLiveData(context: Context?) : LiveData<Float>() { ... override fun onActive() { ... sensorManager?.registerListener(sensorListener, sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_FASTEST) } override fun onInactive() { ... sensorManager.unregisterListener(sensorListener) } } @nisrulz #DCBERLIN18
100. LiveData class MySensorLiveData(context: Context?) : LiveData<Float>() { ... override fun onActive() { ... sensorManager?.registerListener(sensorListener, sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_FASTEST) } override fun onInactive() { ... sensorManager.unregisterListener(sensorListener) } } @nisrulz #DCBERLIN18
101. LiveData val mySensorLiveData = MySensorLiveData(this) // Observe for values mySensorLiveData.observe(this, Observer<Float>{ floatVal -> // Update the UI }) @nisrulz #DCBERLIN18
102. ViewModel @nisrulz #DCBERLIN18
103. ViewModel - Hold & manage UI related data in Lifecycle conscious way - Survives configuration changes - Prevents unnecessary reloading of data @nisrulz #DCBERLIN18
104. ViewModel dependencies { def lifecycle_version = "1.1.1" // For ViewModel implementation "android.arch.lifecycle:viewmodel:$lifecycle_version" ... } @nisrulz #DCBERLIN18
105. ViewModel // Source code public abstract class ViewModel { // Called when ViewModel is destroyed protected void onCleared() { } } @nisrulz #DCBERLIN18
106. ViewModel class MyViewModel : ViewModel() { private val username = MutableLiveData<String>() fun initExpensiveOperation() { // expensive operation, e.g. network request username.value = "Nishant" // username.setValue(“Nishant”) } fun getUsername(): LiveData<String> { return username } } @nisrulz #DCBERLIN18
107. ViewModel class MyViewModel : ViewModel() { private val username = MutableLiveData<String>() fun initExpensiveOperation() { // expensive operation, e.g. network request username.value = "Nishant" // username.setValue(“Nishant”) } fun getUsername(): LiveData<String> { return username } } @nisrulz #DCBERLIN18
108. ViewModel class MyViewModel : ViewModel() { private val username = MutableLiveData<String>() fun initExpensiveOperation() { // expensive operation, e.g. network request username.value = "Nishant" // username.setValue(“Nishant”) } fun getUsername(): LiveData<String> { return username } } @nisrulz #DCBERLIN18
109. ViewModel class MyViewModel : ViewModel() { private val username = MutableLiveData<String>() fun initExpensiveOperation() { // expensive operation, e.g. network request username.value = "Nishant" // username.setValue(“Nishant”) } fun getUsername(): LiveData<String> { return username } } @nisrulz #DCBERLIN18
110. ViewModel class MyViewModel : ViewModel() { private val username = MutableLiveData<String>() fun initExpensiveOperation() { // expensive operation, e.g. network request username.value = "Nishant" // username.setValue(“Nishant”) } fun getUsername(): LiveData<String> { return username } } @nisrulz #DCBERLIN18
111. ViewModel class MyViewModel : ViewModel() { private val username = MutableLiveData<String>() fun initExpensiveOperation() { // expensive operation, e.g. network request username.value = "Nishant" // username.setValue(“Nishant”) } fun getUsername(): LiveData<String> { return username } } @nisrulz #DCBERLIN18
112. ViewModel val viewModel = ViewModelProviders .of(this) .get(MyViewModel::class.java) viewModel.getUsername().observe(this, Observer<String> { text -> //Update the UI }) @nisrulz #DCBERLIN18
113. ViewModel val viewModel = ViewModelProviders .of(this) .get(MyViewModel::class.java) viewModel.getUsername().observe(this, Observer<String> { text -> //Update the UI }) @nisrulz #DCBERLIN18
114. Thank You twitter.com/nisrulz github.com/nisrulz www.nisrulz.com
115. More Info Is your Android Library, Lifecycle-Aware? https://android.jlelse.eu/is-your-android-library-lifecycle-aware-127629d32dcc Official documentation about lifecycle components d.android.com/topic/libraries/architecture/lifecycle Using ProcessLifecycleOwner for libraries example https://github.com/nisrulz/android-examples/tree/develop/UsingProcessLifecycleOwnerForLibs Using Lifecycle Components for libraries example https://github.com/nisrulz/android-examples/tree/develop/LifeCycleCompForLib @nisrulz #DCBERLIN18
116. The A,B and C of Lifecycle Components twitter.com/nisrulz github.com/nisrulz www.nisrulz.com