[Mobius '18] Things I wish I knew when I started building Android Libraries/SDK -Vol 2

Building an Android library in the current times is way different than what it used to be earlier. Things have changed considerably and keeping up to date with them is now a necessity rather than just some acquirable knowledge.

This session is a second part to the last year's talk at Droidcon Berlin 2017 which was Vol. 1. In this session, you will dive deeper into best practices and ways of architecting Android libraries. You will get to learn about the common pitfalls and how to overcome them by using the right approach such as leveraging architecture components and making your Android libraries lifecycle-aware. You will also understand how one can leverage Kotlin language when developing Android libraries as well as information around API design and exploring the path to becoming a better Android Library Developer.

By the end of this session, you will be all set to build Android libraries that scale and have API which contributes to the developer's happiness.

2. OSS Android libraries developed 2
3. Side A 1. How does Gradle process Android Libraries 2. Android Archive(AAR) 3. Why doesn’t my AAR download transitive dependencies? 4. Maven Artifact 5. POM? 6. Bundled Proguard Configs Side B 7. Modularization 8. Avoiding Resource Name Conflicts 9. minSdkVersion Restriction 10. Access Visibility vs Code Organization 11. Lifecycle Aware Android Library 12. Auto Init Android Library 3 @nisrulz
4. How does Gradle process Android Libraries @nisrulz 4
5. How does Gradle process Android Libraries repositories{ jCenter() } dependencies { implementation 'com.example.myawesomelib:1.0.0' ... } 5 @nisrulz
6. How does Gradle process Android Libraries • implementation 6 @nisrulz
7. • api How does Gradle process Android Libraries 7 @nisrulz
8. How does Gradle process Android Libraries • compileOnly 8 @nisrulz
9. Android ARchive(AAR) @nisrulz 9
10. AAR = Java ARchive(JAR) + Resources 10 @nisrulz
11. AAR = Java ARchive(JAR) + Resources Sensey: https://github.com/nisrulz/sensey 11 @nisrulz
12. AAR = Java ARchive(JAR) + Resources @nisrulz 12
13. Sensey’s build.gradle dependencies { ... // Other testing dependencies // Transitive dependency: Support Compat library implementation "com.android.support:support-compat:27.0.2" } 13 @nisrulz
14. Using an AAR as dependency @nisrulz 14
15. Using an AAR as dependency repositories{ flatDir{ dirs 'libs' } } dependencies { implementation(name:'nameOfYourAARFileWithoutExtension', ext:'aar') } @nisrulz 15
16. Using an AAR as dependency repositories{ flatDir{ dirs 'libs' } } dependencies { implementation(name:'nameOfYourAARFileWithoutExtension', ext:'aar') } // No transitive dependencies of the library are downloaded 16 @nisrulz
17. Why doesn’t my AAR download transitive dependencies? @nisrulz 17
18. Sensey’s AAR 18 @nisrulz
19. Sensey’s AAR No build.gradle file 19 @nisrulz
20. Maven Artifact 20 @nisrulz
21. Maven Artifact 21 @nisrulz
22. POM? 22 @nisrulz
23. POM • Project Object Model • XML file • Configuration details used by Maven to build the project 23 @nisrulz
24. POM POM of Sensey Android Library <?xml version="1.0" encoding="UTF-8"?> <project xsi:schemaLocation="..." xmlns="..."xmlns:xsi="..."> <modelVersion>4.0.0</modelVersion> <groupId>com.github.nisrulz</groupId><artifactId>sensey</artifactId><version>1.8.0</version> <packaging>aar</packaging><name>sensey</name> <description>Android library which makes playing with sensor events &amp; detecting gestures a breeze.</description> <url>https://github.com/nisrulz/sensey</url> <licenses> <license> <name>The Apache Software License, Version 2.0</name><url>http://www.apache.org/licenses/LICENSE-2.0.txt</url> </license> </licenses> <developers> <developer><id>nisrulz</id><name>Nishant Srivastava</name><email>nisrulz@gmail.com</email></developer> </developers> <scm> <connection>https://github.com/nisrulz/sensey.git</connection> <developerConnection>https://github.com/nisrulz/sensey.git</developerConnection> <url>https://github.com/nisrulz/sensey</url> </scm> <dependencies> <dependency> <groupId>com.android.support</groupId> <artifactId>support-compat</artifactId><version>27.0.2</version> <scope>runtime</scope> </dependency> <dependency> ... </dependency> </dependencies> </project> 24 @nisrulz
25. POM POM of Sensey Android Library <?xml version="1.0" encoding="UTF-8"?> <project xsi:schemaLocation="..." xmlns="..."xmlns:xsi="..."> <modelVersion>4.0.0</modelVersion> <groupId>com.github.nisrulz</groupId><artifactId>sensey</artifactId><version>1.8.0</version> <packaging>aar</packaging><name>sensey</name> <description>Android library which makes playing with sensor events &amp; detecting gestures a breeze.</description> <url>https://github.com/nisrulz/sensey</url> <licenses> <license> <name>The Apache Software License, Version 2.0</name><url>http://www.apache.org/licenses/LICENSE-2.0.txt</url> </license> </licenses> <developers> <developer><id>nisrulz</id><name>Nishant Srivastava</name><email>nisrulz@gmail.com</email></developer> </developers> <scm> <connection>https://github.com/nisrulz/sensey.git</connection> <developerConnection>https://github.com/nisrulz/sensey.git</developerConnection> <url>https://github.com/nisrulz/sensey</url> </scm> <dependencies> <dependency> <groupId>com.android.support</groupId> <artifactId>support-compat</artifactId><version>27.0.2</version> <scope>runtime</scope> </dependency> <dependency> ... </dependency> </dependencies> </project> 25 @nisrulz
26. POM POM of Sensey Android Library <?xml version="1.0" encoding="UTF-8"?> <project xsi:schemaLocation="..." xmlns="..."xmlns:xsi="..."> ... <dependencies> <dependency> <groupId>com.android.support</groupId> <artifactId>support-compat</artifactId><version>27.0.2</version> <scope>runtime</scope> </dependency> <dependency> ... </dependency> </dependencies> </project> 26 @nisrulz
27. Bundled Proguard Configs 27 @nisrulz
28. Bundled Proguard Configs android { release { minifyEnabled true // Rules to be used during the AAR generation proguardFiles 'proguard-rules-for-building-library.pro' // Rules appended to the integrating app consumerProguardFiles 'proguard-rules-for-using-library.pro' } ... } 28 @nisrulz
29. Bundled Proguard Configs Fuel: https://github.com/kittinunf/Fuel 29 @nisrulz
30. Bundled Proguard Configs 30 @nisrulz
31. Bundled Proguard Configs # Fuel’s bundled Proguard file # Without specifically keeping this class, # callbacks on android don't function properly. -keep class com.github.kittinunf.fuel.android.util.AndroidEnvironment 31 @nisrulz
32. Bundled Proguard Configs # To check the merged configuration # Add the below to your current config -printconfiguration proguard-merged-config.txt 32 @nisrulz
33. Bundled Proguard Configs # DON'T DO THIS -dontobfuscate -optimizations !code/allocation/variable # Effectively no optimizations -keep public class * { public protected *; } 33 @nisrulz
34. Bundled Proguard Configs # DON'T DO THIS # Adding the below in library proguard rules disables # the optimizations in the Android app -dontoptimize 34 @nisrulz
35. Modularization 35 @nisrulz
36. Modularization 36 @nisrulz
37. Modularization EasyDeviceInfo: https://github.com/nisrulz/easydeviceinfo 37 @nisrulz
38. Modularization dependencies { def libVer = {latest_version} // Base + Ads Bundled Library implementation "com.github.nisrulz:easydeviceinfo:$libVer" // Base Library implementation "com.github.nisrulz:easydeviceinfo-base:$libVer" // Ads Library implementation "com.github.nisrulz:easydeviceinfo-ads:$libVer" } 38 @nisrulz
39. Modularization <!-- POM file for com.github.nisrulz:easydeviceinfo --> <project xsi:schemaLocation="..." xmlns="..." xmlns:xsi="..."> ... <dependencies> <dependency> <groupId>com.github.nisrulz</groupId> <artifactId>easydeviceinfo-ads</artifactId> <version>2.5.0</version> <scope>compile</scope> </dependency> <dependency> <groupId>com.github.nisrulz</groupId> <artifactId>easydeviceinfo-base</artifactId> <version>2.5.0</version> <scope>compile</scope> </dependency> ... </dependencies> </project> 39 @nisrulz
40. Modularization <!-- POM file for com.github.nisrulz:easydeviceinfo--> <project xsi:schemaLocation="..." xmlns="..." xmlns:xsi="..."> ... <dependencies> <dependency> <groupId>com.github.nisrulz</groupId> <artifactId>easydeviceinfo-ads</artifactId> <version>2.5.0</version> <scope>compile</scope> </dependency> <dependency> <groupId>com.github.nisrulz</groupId> <artifactId>easydeviceinfo-base</artifactId> <version>2.5.0</version> <scope>compile</scope> </dependency> ... </dependencies> </project> 40 @nisrulz
41. Modularization <!-- POM file for com.github.nisrulz:easydeviceinfo--> <project xsi:schemaLocation="..." xmlns="..." xmlns:xsi="..."> ... <dependencies> <dependency> <groupId>com.github.nisrulz</groupId> <artifactId>easydeviceinfo-ads</artifactId> <version>2.5.0</version> <scope>compile</scope> </dependency> <dependency> <groupId>com.github.nisrulz</groupId> <artifactId>easydeviceinfo-base</artifactId> <version>2.5.0</version> <scope>compile</scope> </dependency> ... </dependencies> </project> 41 @nisrulz
42. Modularization <!-- POM file for com.github.nisrulz:easydeviceinfo-ads --> <project xsi:schemaLocation="..." xmlns="..." xmlns:xsi="..."> ... <dependencies> <dependency> <groupId>com.github.nisrulz</groupId> <artifactId>easydeviceinfo-common</artifactId><version>2.5.0</version> <scope>compile</scope> </dependency> <dependency> <groupId>com.google.android.gms</groupId> <artifactId>play-services-ads-identifier</artifactId><version>16.0.0</version> <scope>runtime</scope> </dependency> ... </dependencies> </project> 42 @nisrulz
43. Modularization <!-- POM file for com.github.nisrulz:easydeviceinfo-ads --> <project xsi:schemaLocation="..." xmlns="..." xmlns:xsi="..."> ... <dependencies> <dependency> <groupId>com.github.nisrulz</groupId> <artifactId>easydeviceinfo-common</artifactId><version>2.5.0</version> <scope>compile</scope> </dependency> <dependency> <groupId>com.google.android.gms</groupId> <artifactId>play-services-ads-identifier</artifactId><version>16.0.0</version> <scope>runtime</scope> </dependency> ... </dependencies> </project> 43 @nisrulz
44. Avoiding Resource Name Conflicts 44 @nisrulz
45. Conflict occurs between a library & app resource > Project will not compile What happens when... 45 @nisrulz
46. Conflict occurs between 2 libraries integrated in the app > Resources from library defined first in build.gradle gets included What happens when... 46 @nisrulz
47. Solution? 47 @nisrulz
48. Add a prefix to all your resources. Solution? 48 @nisrulz
49. Add a prefix to all your resources. How? Solution? 49 @nisrulz
50. Add a prefix to all your resources. How? • Enforce this in Android Studio Solution? 50 @nisrulz
51. Add a prefix to all your resources. How? • Enforce this in Android Studio • Declare in build.gradle of library android { resourcePrefix 'YOUR_PREFIX_' // i.e 'sensey_' } Solution? 51 @nisrulz
52. Solution? Resource named ‘app_name’ does not start with the project’s resource prefix ‘sensey_’; Rename to `sensey_app_name`? 52 @nisrulz
53. minSdkVersion Restriction 53 @nisrulz
54. minSdkVersion of app >= minSdkVersion of library minSdk Restriction 54 @nisrulz
55. minSdk Restriction 55 @nisrulz
56. Manifest merger failed : uses-sdk:minSdkVersion 14 cannot be smaller than version 21 declared in library [:sensey] Suggestion: + Use a compatible library with a minSdk of at most 14 + Increase this project's minSdk version to at least 21 + Use tools:overrideLibrary="com.github.nisrulz.sensey" to force usage (may lead to runtime failures) minSdk Restriction 56 @nisrulz
57. Manifest merger failed : uses-sdk:minSdkVersion 14 cannot be smaller than version 21 declared in library [:sensey] Suggestion: + Use a compatible library with a minSdk of at most 14 + Increase this project's minSdk version to at least 21 + Use tools:overrideLibrary="com.github.nisrulz.sensey" to force usage (may lead to runtime failures) minSdk Restriction 57 @nisrulz
58. Manifest merger failed : uses-sdk:minSdkVersion 14 cannot be smaller than version 21 declared in library [:sensey] Suggestion: + Use a compatible library with a minSdk of at most 14 + Increase this project's minSdk version to at least 21 + Use tools:overrideLibrary="com.github.nisrulz.sensey" to force usage (may lead to runtime failures) minSdk Restriction 58 @nisrulz
59. <manifest xmlns:android="..." xmlns:tools="http://schemas.android.com/tools" package="com.github.nisrulz.senseysample"> <uses-sdk tools:overrideLibrary="com.github.nisrulz.sensey"/> <application ...> ... </application> </manifest> minSdk Restriction 59 @nisrulz
60. <manifest xmlns:android="..." xmlns:tools="http://schemas.android.com/tools" package="com.github.nisrulz.senseysample"> <uses-sdk tools:overrideLibrary="com.github.nisrulz.sensey"/> <application ...> ... </application> </manifest> minSdk Restriction 60 @nisrulz
61. Access Visibility vs Code Organization 61 @nisrulz
62. Visibility vs Organization 62 @nisrulz
63. Visibility vs Organization • Code organized in individual packages; everything is public 63 @nisrulz
64. Visibility vs Organization • Code organized inside one package; everything is package private and only public on demand 64 @nisrulz
65. Visibility vs Organization • Code organized inside the module i.e individual packages; everything is internal and only public on demand (in Kotlin land) • Drawback ◦ Need dependency on kotlin std library 65 @nisrulz
66. Visibility vs Organization // file name: exampleLibrary.kt // module name: example package com.example.library 66 @nisrulz
67. Visibility vs Organization // file name: exampleLibrary.kt // module name: example package com.example.library // visible inside exampleLibrary.kt private fun setup() { ... } 67 @nisrulz
68. Visibility vs Organization // file name: exampleLibrary.kt // module name: example package com.example.library // visible inside exampleLibrary.kt private fun setup() { ... } // property is visible everywhere public var name: String = "ExampleLib" // setter is visible only in exampleLibrary.kt private set{...} 68 @nisrulz
69. Visibility vs Organization // file name: exampleLibrary.kt // module name: example package com.example.library // visible inside exampleLibrary.kt private fun setup() { ... } // property is visible everywhere public var name: String = "ExampleLib" // setter is visible only in exampleLibrary.kt private set{...} // visible inside the module i.e example internal val debugTag = "Example-Debug" 69 @nisrulz
70. Lifecycle-Aware Android Library 70 @nisrulz
71. Lifecycle Components Classes designed to help deal with Android lifecycle • Lifecycle • LifecycleOwner • LifecycleObserver 71 @nisrulz
72. Lifecycle Components Classes designed to help deal with Android lifecycle 72 @nisrulz
73. Lifecycle Components Classes designed to help deal with Android lifecycle i.e Activity, Fragment, Service, Custom 73 @nisrulz
74. Lifecycle class MainActivity extends AppCompatActivity() {...} 74 @nisrulz
75. Lifecycle class MainActivity extends AppCompatActivity() {...} public class AppCompatActivity extends FragmentActivity{...} 75 @nisrulz
76. Lifecycle class MainActivity extends AppCompatActivity() {...} public class AppCompatActivity extends FragmentActivity{...} public class FragmentActivity extends SupportActivity { ... public Lifecycle getLifecycle() { return super.getLifecycle(); } ... } 76 @nisrulz
77. LifecycleObserver dependencies { def lifecycleVer = "2.0.0" // Runtime implementation "androidx.lifecycle:lifecycle-runtime:$lifecycleVer" // Annotation Support annotationProcessor "androidx.lifecycle:lifecycle-compiler:$lifecycleVer" ... } 77 @nisrulz
78. LifecycleObserver public class AwesomeLib implements LifecycleObserver { @OnLifecycleEvent(Lifecycle.Event.ON_CREATE) public void init() { ... } @OnLifecycleEvent(Lifecycle.Event.ON_START) public void libOnStart() { ... } ... @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY) public void cleanup() { ... } } 78 @nisrulz
79. LifecycleOwner class MainActivity : AppCompatActivity() { val awesomeLib = AwesomeLib() override fun onResume() { ... // Add lifecycle observer lifecycle.addObserver(awesomeLib) } override fun onStop() { ... // Remove lifecycle observer lifecycle.removeObserver(awesomeLib) } } 79 @nisrulz
80. LifecycleAware Library 80 @nisrulz
81. ProcessLifecycleOwner Class that tracks the lifecycle of whole application process 81 @nisrulz
82. ProcessLifecycleOwner dependencies { // For ProcessLifecycleOwner implementation "androidx.lifecycle:lifecycle-extensions:2.0.0" ... } 82 @nisrulz
83. ProcessLifecycleOwner Does something weird… 83 @nisrulz
84. ProcessLifecycleOwner Does something weird… Adding lifecycle-extensions artifact > automatically adds <provider> element to the merged manifest 84 @nisrulz
85. ProcessLifecycleOwner 85 @nisrulz
86. ProcessLifecycleOwner <manifest > <application> ... <provider android:name="androidx.lifecycle.ProcessLifecycleOwnerInitializer" android:authorities="com.example.app.lifecycle-process" android:exported="false" android:multiprocess="true" /> </application> </manifest> 86 @nisrulz
87. ProcessLifecycleOwner <manifest > <application> ... <provider android:name="androidx.lifecycle.ProcessLifecycleOwnerInitializer" android:authorities="com.example.app.lifecycle-process" android:exported="false" android:multiprocess="true" /> </application> </manifest> 87 @nisrulz
88. 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> 88 @nisrulz Pre-AndroidX
89. 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> 89 @nisrulz Pre-AndroidX
90. ProcessLifecycleOwner 90 @nisrulz Pre-AndroidX
91. ProcessLifecycleOwner <manifest > <application> ... <provider android:name="androidx.lifecycle.ProcessLifecycleOwnerInitializer" android:authorities="com.example.app.lifecycle-process" android:exported="false" android:multiprocess="true" /> </application> </manifest> 91 @nisrulz AndroidX
92. ProcessLifecycleOwner <manifest > <application> ... <provider android:name="androidx.lifecycle.ProcessLifecycleOwnerInitializer" android:authorities="com.example.app.lifecycle-process" android:exported="false" android:multiprocess="true" /> </application> </manifest> 92 @nisrulz AndroidX
93. ProcessLifecycleOwner // Internal class to initialize Lifecycles. public class ProcessLifecycleOwnerInitializer extends ContentProvider { @Override public boolean onCreate() { ... ProcessLifecycleOwner.init(getContext()); return true; } ... } 93 @nisrulz
94. ProcessLifecycleOwner Why? To invoke ProcessLifecycleOwner as soon as process starts 94 @nisrulz
95. ProcessLifecycleOwner Why? To invoke ProcessLifecycleOwner as soon as process starts Drawback? Initializes ProcessLifecycleOwner even if your app does not use it! 95 @nisrulz
96. ProcessLifecycleOwner How to get rid of it in app? 96 @nisrulz
97. ProcessLifecycleOwner How to get rid of it in app? Use Merge rule marker in app’s AndroidManifest.xml: // Remove marked element from the merged manifest tools:node="remove" 97 @nisrulz
98. ProcessLifecycleOwner <application> ... <provider android:name="androidx.lifecycle.ProcessLifecycleOwnerInitializer" android:authorities="${applicationId}.lifecycle-process" xmlns:tools="http://schemas.android.com/tools" tools:node="remove" /> </application> 98 @nisrulz App’s AndroidManifest.xml
99. ProcessLifecycleOwner <application> ... <provider android:name="androidx.lifecycle.ProcessLifecycleOwnerInitializer" android:authorities="${applicationId}.lifecycle-process" xmlns:tools="http://schemas.android.com/tools" tools:node="remove" /> </application> 99 @nisrulz App’s AndroidManifest.xml
100. ProcessLifecycleOwner <application> ... <provider android:name="androidx.lifecycle.ProcessLifecycleOwnerInitializer" android:authorities="${applicationId}.lifecycle-process" xmlns:tools="http://schemas.android.com/tools" tools:node="remove" /> </application> 100 @nisrulz App’s AndroidManifest.xml
101. ProcessLifecycleOwner <application> ... <provider android:name="androidx.lifecycle.ProcessLifecycleOwnerInitializer" android:authorities="${applicationId}.lifecycle-process" xmlns:tools="http://schemas.android.com/tools" tools:node="remove" /> </application> 101 @nisrulz App’s AndroidManifest.xml
102. Auto Initialize Android Library 102 @nisrulz
103. AutoInit Android Library Android Libraries need Android context to handle simple tasks such as • Hook into Android Runtime • Access app resources • Use System Services • Register BroadcastReceiver 103 @nisrulz
104. AutoInit Android Library public class MyApplication extends Application { @Override public void onCreate() { super.onCreate(); // Init android library MyAwesomeLibrary.init(this); } } 104 @nisrulz
105. AutoInit Android Library public class MyApplication extends Application { @Override public void onCreate() { super.onCreate(); // Init android library MyAwesomeLibrary.init(this); } } 105 @nisrulz
106. AutoInit Android Library public class MyApplication extends Application { @Override public void onCreate() { super.onCreate(); // Init android library MyAwesomeLibrary.init(this); } } 106 @nisrulz
107. AutoInit Android Library <application android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:name=".MyApplication" ... > 107 @nisrulz
108. AutoInit Android Library <application android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:name=".MyApplication" ... > 108 @nisrulz
109. AutoInit Android Library ContentProvider can be used to simplify the process. 109 @nisrulz
110. AutoInit Android Library ContentProvider can be used to simplify the process. Simply because ContentProvider • Is created and initialized (on the main thread) before all other components • Participate in manifest merging at build time. 110 @nisrulz
111. AutoInit Android Library public class AwesomeLibInitProvider extends ContentProvider { ... @Override public boolean onCreate() { // get the context (Application context) Context context = getContext(); // initialize AwesomeLib here AwesomeLib.getInstance().init(context); return false; } ... } 111 @nisrulz
112. AutoInit Android Library public class AwesomeLibInitProvider extends ContentProvider { ... @Override public boolean onCreate() { // get the context (Application context) Context context = getContext(); // initialize AwesomeLib here AwesomeLib.getInstance().init(context); return false; } ... } 112 @nisrulz
113. AutoInit Android Library <manifest xmlns:android=".." package="github.nisrulz.sample.awesomelib"> <application> <provider android:name=".AwesomeLibInitProvider" android:authorities="${applicationId}.awesomelibinitprovider" android:enabled="true" android:exported="false"/> </application> </manifest> 113 @nisrulz
114. AutoInit Android Library <manifest xmlns:android=".." package="github.nisrulz.sample.awesomelib"> <application> <provider android:name=".AwesomeLibInitProvider" android:authorities="${applicationId}.awesomelibinitprovider" android:enabled="true" android:exported="false"/> </application> </manifest> 114 @nisrulz
115. AutoInit Android Library <manifest xmlns:android=".." package="github.nisrulz.sample.awesomelib"> <application> <provider android:name=".AwesomeLibInitProvider" android:authorities="${applicationId}.awesomelibinitprovider" android:enabled="true" android:exported="false"/> </application> </manifest> 115 @nisrulz
116. AutoInit Android Library <manifest xmlns:android=".." package="github.nisrulz.sample.awesomelib"> <application> <provider android:name=".AwesomeLibInitProvider" android:authorities="${applicationId}.awesomelibinitprovider" android:enabled="true" android:exported="false"/> </application> </manifest> 116 @nisrulz
117. AutoInit Android Library ContentProvider can be used to simplify the process. 117 @nisrulz
118. AutoInit Android Library ContentProvider can be used to simplify the process. Challenges: • There can be only one Content Provider with a given “authority” string • Only run on main thread 118 @nisrulz
119. AutoInit Android Library ContentProvider can be used to simplify the process. 119 @nisrulz
120. AutoInit Android Library ContentProvider can be used to simplify the process. Why this is a bad idea: • Increases startup time • Bloats applications even when not used • Abusing functionality of ContentProvider 120 @nisrulz
121. AutoInit Android Library ContentProvider can be used to simplify the process. Why this is a bad idea: • Increases startup time (Solution: async initialize) • Bloats applications even when not used • Abusing functionality of ContentProvider 121 @nisrulz
122. AutoInit Android Library Some android libraries that use this... 122 @nisrulz
123. AutoInit Android Library ProcessLifecycleOwner [androidx.lifecycle:lifecycle-extensions:2.0.0] <application> <provider android:name="androidx.lifecycle.ProcessLifecycleOwnerInitializer" android:authorities="${applicationId}.lifecycle-process" android:exported="false" android:multiprocess="true" /> </application> 123 @nisrulz
124. AutoInit Android Library Firebase [com.google.firebase:firebase-common:16.0.5] <application> <provider android:name="com.google.firebase.provider.FirebaseInitProvider" android:authorities="${applicationId}.firebaseinitprovider" android:exported="false" android:initOrder="100" /> </application> 124 @nisrulz
125. AutoInit Android Library Facebook-Core [com.facebook.android:facebook-core:4.34.0] <application> <provider android:name="com.facebook.internal.FacebookInitProvider" android:authorities="${applicationId}.FacebookInitProvider" android:exported="false" /> </application> 125 @nisrulz
126. AutoInit Android Library Facebook-Marketing [com.facebook.android:facebook-marketing:4.34.0] <application> <provider android:name="com.facebook.marketing.internal.MarketingInitProvider" android:authorities="${applicationId}.MarketingInitProvider" android:exported="false" /> </application> 126 @nisrulz
127. AutoInit Android Library Crashlytics [com.crashlytics.sdk.android:crashlytics:2.9.5] <application> <provider android:name="com.crashlytics.android.CrashlyticsInitProvider" android:authorities="${applicationId}.crashlyticsinitprovider" android:exported="false" android:initOrder="90" /> </application> 127 @nisrulz
128. AutoInit Android Library Picasso // Pre - v2.71828 Picasso.with(this).load("...<url>...").into(imageView); // After - v2.71828 Picasso.get().load("...<url>...").into(imageView); 128 @nisrulz
129. AutoInit Android Library Picasso // Pre - v2.71828 Picasso.with(this).load("...<url>...").into(imageView); // After - v2.71828 Picasso.get().load("...<url>...").into(imageView); 129 @nisrulz
130. AutoInit Android Library Picasso [com.squareup.picasso:picasso:2.71828] <application> <provider android:name=".PicassoContentProvider" android:authorities="${applicationId}.com.squareup.picasso3" android:exported="false"/> </application> 130 @nisrulz
131. Links/References Android Libraries I have built: https://github.com/nisrulz/nisrulz.github.io#open-source-co ntributions Auto initialize android library example: https://github.com/nisrulz/android-examples/tree/develop/Au toInitLibrary Lifecycle Aware android library example: https://github.com/nisrulz/android-examples/tree/develop/Li feCycleCompForLib 131 @nisrulz
132. twitter.com/nisrulz github.com/nisrulz www.nisrulz.com 132
133. twitter.com/nisrulz github.com/nisrulz www.nisrulz.com 133