Build.Better.­Android.Libraries

As more and more people start building Android Libraries, the whole process of building a better API for developers is getting bloated and everyone is coming up with their own ideas. However, if android library developers follow a certain standard with a rationale they can avoid most of the pitfalls. Building an android library is easy, but building one that keeps in mind developer happiness is rare but definitely not hard. The session would cover how one can build android libraries taking in consideration to exposing more informative API, making sure the best resources are utilized efficiently and that one does not force the app developer with redundant dependencies and complexities.

Working Gif Version: https://goo.gl/HQFX7n

Transcript

1. Build.Better. Android.Libraries Nishant Srivastava @nisrulz
2. About me Nishant Srivastava Software Engineer/Founding Team Member (at) Omni Labs, Inc. Lead Organizer (at) GDG, New Delhi, India Open Source enthusiast @nisrulz
3. Before we begin... @nisrulz
4. What Is an Android Library? @nisrulz
5. Android Library is... ...simply put, pre-written reusable logic in code, for android apps... @nisrulz
6. Android Library is... ...simply put, pre-written reusable logic in code, for android apps... @nisrulz
7. Android Library is... Java code + <secret ingredient> + <secret ingredient> = @nisrulz
8. Android Library is... Java code + android resources + <secret ingredient> = @nisrulz
9. Android Library is... Java code + android resources + android manifest stub = @nisrulz
10. Android Library is... Java code + android resources + android manifest stub = Android ARchive (AAR) @nisrulz
11. Why create an Android Library? @nisrulz
12. Why create an Android Library? Short Answer @nisrulz
13. Why create an Android Library? Short Answer You don’t have to @nisrulz
14. Why create an Android Library? Short Answer You don’t have to @nisrulz If a solution already exists, use it
15. Best Practices for building android libraries... @nisrulz ...with that, let us move on to
16. Ease of use Intuitive @nisrulz
17. Ease of use Intuitive ◦ It should do what the user of android library expects it to do without having to look up the documentation. @nisrulz
18. Ease of use Intuitive ◦ It should do what the user of android library expects it to do without having to look up the documentation. Consistent @nisrulz
19. Ease of use Intuitive ◦ It should do what the user of android library expects it to do without having to look up the documentation. Consistent ◦ The code for the android library should be well thought and should not change drastically between versions @nisrulz
20. Ease of use Intuitive ◦ It should do what the user of android library expects it to do without having to look up the documentation. Consistent ◦ The code for the android library should be well thought and should not change drastically between versions Easy to use, hard to misuse @nisrulz
21. Ease of use Intuitive ◦ It should do what the user of android library expects it to do without having to look up the documentation. Consistent ◦ The code for the android library should be well thought and should not change drastically between versions Easy to use, hard to misuse ◦ Validation checks, sane defaults, handle errors @nisrulz
22. Avoid multiple arguments @nisrulz
23. Avoid multiple arguments // Do not DO this void init(String apikey, int refresh, long interval, String type, String username, String email, String password); @nisrulz
24. Avoid multiple arguments // Do not DO this void init(String apikey, int refresh, long interval, String type, String username, String email, String password); @nisrulz // WHY?
25. Avoid multiple arguments // Do not DO this void init(String apikey, int refresh, long interval, String type, String username, String email, String password); @nisrulz // WHY? void init(“0123456789”, true, 1000, “prod”, “nishant”, ”1234”, “nisrulz@gmail.com”);
26. Avoid multiple arguments // Do not DO this void init(String apikey, int refresh, long interval, String type, String username, String email, String password); @nisrulz // WHY? void init(“0123456789”, true, 1000, “prod”, “nishant”, ”1234”, “nisrulz@gmail.com”); // Easy to mess up things here :(
27. Avoid multiple arguments // Do not DO this void init(String apikey, int refresh, long interval, String type, String username, String email, String password); @nisrulz // DO this void init(ApiSecret apisecret);
28. // where ApiSecret public class ApiSecret{ String apikey; int refresh; long interval; String type; String name; String email; String pass; // constructor /* you can define proper checks(such as type safety) and * conditions to validate data before it gets set */ // setter and getters } @nisrulz
29. Avoid multiple arguments // Do not DO this boolean init(String apikey, int refresh, long interval, String type, String username, String email, String password); @nisrulz // DO this boolean init(ApiSecret apisecret); // Or use a Builder Pattern
30. // Builder Pattern AwesomeLib awesomelib = new AwesomeLib.AwesomeLibBuilder() .apisecret(mApisecret) .refresh(mRefresh) .interval(mInterval) .type(mType) .username(mUsername) .email(mEmail) .password(mPassword) .build(); } @nisrulz
31. Minimize Permissions Use Intents @nisrulz
32. Minimize Permissions Use Intents ◦ Let dedicated apps do the work for you. @nisrulz
33. Minimize Permissions Use Intents ◦ Let dedicated apps do the work for you. Reduce the no. of permissions @nisrulz
34. Minimize Permissions Use Intents ◦ Let dedicated apps do the work for you. Reduce the no. of permissions Check for permission, use fallbacks @nisrulz
35. Minimize Permissions Use Intents ◦ Let dedicated apps do the work for you. Reduce the no. of permissions Check for permission, use fallbacks ◦ public boolean hasPermission(Context context, String permission) { int result = context.checkCallingOrSelfPermission(permission); return result == PackageManager.PERMISSION_GRANTED; } @nisrulz
36. Minimize Requisites // Do not do this <uses-feature android:name="android.hardware.bluetooth" /> @nisrulz
37. Minimize Requisites // Do not do this <uses-feature android:name="android.hardware.bluetooth" /> // Use this String feature = PackageManager.FEATURE_BLUETOOTH; public boolean isFeatureAvailable(Context context, String feature) { return context.getPackageManager().hasSystemFeature(feature); } @nisrulz
38. Minimize Requisites // Do not do this <uses-feature android:name="android.hardware.bluetooth" /> // Use this String feature = PackageManager.FEATURE_BLUETOOTH; public boolean isFeatureAvailable(Context context, String feature) { return context.getPackageManager().hasSystemFeature(feature); } // Enable/Disable the functionality dependent on the // feature as per requirement @nisrulz
39. Support different versions /* RULE OF THUMB : Support the full spectrum of android * versions */ @nisrulz
40. Support different versions /* RULE OF THUMB : Support the full spectrum of android * versions */ android { ... defaultConfig { .. minSdkVersion 9 targetSdkVersion 25 .. } } @nisrulz
41. Support different versions /* RULE OF THUMB : Enable/Disable features or use a fallback * based on detected version */ @nisrulz
42. Support different versions /* RULE OF THUMB : Enable/Disable features or use a fallback * based on detected version */ // Method to check if the Android Version on the device is greater than or equal to Marshmallow. public boolean isMarshmallow(){ return Build.VERSION.SDK_INT>= Build.VERSION_CODES.M; } @nisrulz
43. Do not log in production @nisrulz
44. Do not log in production @nisrulz ...just Don’t. Seriously don’t.
45. Do not log in production Use Build Variants @nisrulz
46. Do not log in production Use Build Variants Flagged Logging @nisrulz
47. Do not log in production Use Build Variants Flagged Logging ◦ MyAwesomeLibrary.init(apisecret,BuildConfig.DEBUG); @nisrulz
48. Do not log in production Use proguard // add to your proguard file -assumenosideeffects class android.util.Log { public static boolean isLoggable(java.lang.String, int); public static int v(...); public static int i(...); public static int w(...); public static int d(...); public static int e(...); } @nisrulz
49. Do not log in production Use proguard // enable proguard in build.gradle, switch to proguard-android-optimize .txt android { ... buildTypes { release { ... minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android-optimize .txt'), 'proguard-rules.pro' } } } @nisrulz
50. … we do not want this to happen! @nisrulz
51. Do not crash silently and fail fast @nisrulz Log Errors and Exception
52. // Provide flexibility to log when debug flag is true void init(ApiSecret apisecret,boolean debuggable){ ... try{ ... } catch(Exception ex){ If (debuggable){ // This is printed only when debuggable is true ex.printStackTrace(); } } .... } @nisrulz
53. Degrade gracefully in an event of an error @nisrulz Don’t crash the app, Disable functionality
54. Catch specific exception @nisrulz // Do not do this try { // ... } catch(Exception e) { // ... }
55. Catch specific exception @nisrulz // Do this try { // ... } catch(NullpointerException e) { // ... }
56. @nisrulz
57. Handle poor network conditions @nisrulz
58. Handle poor network conditions 1. Prepare for unreliable/flaky network conditions @nisrulz
59. Handle poor network conditions 1. Prepare for unreliable/flaky network conditions 2. Batch your network calls @nisrulz
60. Handle poor network conditions 1. Prepare for unreliable/flaky network conditions 2. Batch your network calls 3. Prefetch data ahead of time @nisrulz
61. Handle poor network conditions 1. Prepare for unreliable/flaky network conditions 2. Batch your network calls 3. Prefetch data ahead of time 4. Replace JSON/XML with flatbuffers @nisrulz
62. Handle poor network conditions 1. Prepare for unreliable/flaky network conditions 2. Batch your network calls 3. Prefetch data ahead of time 4. Replace JSON/XML with flatbuffers @nisrulz
63. @nisrulz
64. @nisrulz
65. @nisrulz
66. Reluctance to include large libraries as dependencies @nisrulz
67. Reluctance to include large libraries as dependencies WHY ? @nisrulz
68. Reluctance to include large libraries as dependencies WHY ? Methods Counts! @nisrulz
69. Do not require dependencies unless you very much have to Avoid bloating the library with dependencies @nisrulz
70. Do not require dependencies unless you very much have to Get the developer to provide you those dependencies @nisrulz
71. Do not require dependencies unless you very much have to Get the developer to provide you those dependencies dependencies { // for gradle version 2.12 and below provided 'com.squareup.okhttp3:okhttp:3.7.0' // or for gradle version 2.12+ compileOnly 'com.squareup.okhttp3:okhttp:3.7.0' } @nisrulz
72. Do not require dependencies unless you very much have to Enable/disable features based on availability of dependency @nisrulz
73. Do not require dependencies unless you very much have to Enable/disable features based on availability of dependency private boolean hasOKHttpOnClasspath() { try { Class.forName("com.squareup.okhttp3.OkHttpClient"); return true; } catch (ClassNotFoundException ex) { ex.printStackTrace(); } return false; } @nisrulz
74. Try not to hog the startup @nisrulz
75. Try not to hog the startup @nisrulz
76. Remove features and functionalities gracefully @nisrulz
77. Remove features and functionalities gracefully Mark @Deprecated before removing a public API
78. Make your code testable @nisrulz
79. Document Everything! @nisrulz
80. Document Everything! 1. Create a Readme.md file @nisrulz
81. Document Everything! 1. Create a Readme.md file 2. Have Javadoc comments @nisrulz
82. Document Everything! 1. Create a Readme.md file 2. Have Javadoc comments 3. Bundle a sample app @nisrulz
83. Document Everything! 1. Create a Readme.md file 2. Have Javadoc comments 3. Bundle a sample app 4. Keep a detailed changelog of releases @nisrulz
84. Document Everything! @nisrulz
85. Provide a most minimalistic sample app @nisrulz
86. Consider putting up a license @nisrulz https://choosealicense.com/
87. Get feedback, lots of them @nisrulz
88. As a rule of thumb follow the rule of SPOIL-ing your Library Simple — Briefly and Clearly expressed Purposeful — Having or showing resolve Opensource — Universal Access, Free license Idiomatic — Natural to the native environment Logical — Clear, Sound Reasoning @nisrulz
89. References BlogPost: https://android.jlelse.eu/things-i-wish-i-knew-when-i-started-bu ilding-android-sdk-libraries-dba1a524d619 Open Source android libraries I have made: https://github.com/nisrulz/nisrulz.github.io#android-librariessdk @nisrulz
90. Thank You Questions? @nisrulz