Build.Better.Android.Libraries

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Build.Better. Android.Libraries Nishant Srivastava @nisrulz

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About me Nishant Srivastava Software Engineer/Founding Team Member (at) Omni Labs, Inc. Lead Organizer (at) GDG, New Delhi, India Open Source enthusiast @nisrulz

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Before we begin... @nisrulz

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What Is an Android Library? @nisrulz

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Android Library is... ...simply put, pre-written reusable logic in code, for android apps... @nisrulz

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Android Library is... ...simply put, pre-written reusable logic in code, for android apps... @nisrulz

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Android Library is... Java code + + = @nisrulz

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Android Library is... Java code + android resources + = @nisrulz

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Android Library is... Java code + android resources + android manifest stub = @nisrulz

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Android Library is... Java code + android resources + android manifest stub = Android ARchive (AAR) @nisrulz

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Why create an Android Library? @nisrulz

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Why create an Android Library? Short Answer @nisrulz

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Why create an Android Library? Short Answer You don’t have to @nisrulz

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Why create an Android Library? Short Answer You don’t have to @nisrulz If a solution already exists, use it

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Best Practices for building android libraries... @nisrulz ...with that, let us move on to

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Ease of use Intuitive @nisrulz

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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

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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

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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

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Avoid multiple arguments @nisrulz

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Avoid multiple arguments // Do not DO this void init(String apikey, int refresh, long interval, String type, String username, String email, String password); @nisrulz

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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?

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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”);

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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);

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// 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

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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

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// Builder Pattern AwesomeLib awesomelib = new AwesomeLib.AwesomeLibBuilder() .apisecret(mApisecret) .refresh(mRefresh) .interval(mInterval) .type(mType) .username(mUsername) .email(mEmail) .password(mPassword) .build(); } @nisrulz

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Minimize Permissions Use Intents @nisrulz

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Minimize Permissions Use Intents ○ Let dedicated apps do the work for you. @nisrulz

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Minimize Permissions Use Intents ○ Let dedicated apps do the work for you. Reduce the no. of permissions @nisrulz

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Minimize Permissions Use Intents ○ Let dedicated apps do the work for you. Reduce the no. of permissions Check for permission, use fallbacks @nisrulz

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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

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Minimize Requisites // Do not do this @nisrulz

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Minimize Requisites // Do not do this // Use this String feature = PackageManager.FEATURE_BLUETOOTH; public boolean isFeatureAvailable(Context context, String feature) { return context.getPackageManager().hasSystemFeature(feature); } @nisrulz

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Support different versions /* RULE OF THUMB : Support the full spectrum of android * versions */ @nisrulz

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Support different versions /* RULE OF THUMB : Support the full spectrum of android * versions */ android { ... defaultConfig { .. minSdkVersion 9 targetSdkVersion 25 .. } } @nisrulz

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Support different versions /* RULE OF THUMB : Enable/Disable features or use a fallback * based on detected version */ @nisrulz

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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

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Do not log in production @nisrulz

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Do not log in production @nisrulz ...just Don’t. Seriously don’t.

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Do not log in production Use Build Variants @nisrulz

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Do not log in production Use Build Variants Flagged Logging @nisrulz

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Do not log in production Use Build Variants Flagged Logging ○ MyAwesomeLibrary.init(apisecret,BuildConfig.DEBUG); @nisrulz

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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

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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

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… we do not want this to happen! @nisrulz

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Do not crash silently and fail fast @nisrulz Log Errors and Exception

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// 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

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Degrade gracefully in an event of an error @nisrulz Don’t crash the app, Disable functionality

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Catch specific exception @nisrulz // Do not do this try { // ... } catch(Exception e) { // ... }

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Catch specific exception @nisrulz // Do this try { // ... } catch(NullpointerException e) { // ... }

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@nisrulz

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Handle poor network conditions @nisrulz

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Handle poor network conditions 1. Prepare for unreliable/flaky network conditions @nisrulz

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Handle poor network conditions 1. Prepare for unreliable/flaky network conditions 2. Batch your network calls @nisrulz

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Handle poor network conditions 1. Prepare for unreliable/flaky network conditions 2. Batch your network calls 3. Prefetch data ahead of time @nisrulz

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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

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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

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@nisrulz

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@nisrulz

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@nisrulz

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Reluctance to include large libraries as dependencies @nisrulz

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Reluctance to include large libraries as dependencies WHY ? @nisrulz

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Reluctance to include large libraries as dependencies WHY ? Methods Counts! @nisrulz

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Do not require dependencies unless you very much have to Avoid bloating the library with dependencies @nisrulz

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Do not require dependencies unless you very much have to Get the developer to provide you those dependencies @nisrulz

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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

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Do not require dependencies unless you very much have to Enable/disable features based on availability of dependency @nisrulz

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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

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Try not to hog the startup @nisrulz

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Try not to hog the startup @nisrulz

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Remove features and functionalities gracefully @nisrulz

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Remove features and functionalities gracefully Mark @Deprecated before removing a public API

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Make your code testable @nisrulz

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Document Everything! @nisrulz

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Document Everything! 1. Create a Readme.md file @nisrulz

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Document Everything! 1. Create a Readme.md file 2. Have Javadoc comments @nisrulz

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Document Everything! 1. Create a Readme.md file 2. Have Javadoc comments 3. Bundle a sample app @nisrulz

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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

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Document Everything! @nisrulz

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Provide a most minimalistic sample app @nisrulz

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Consider putting up a license @nisrulz https://choosealicense.com/

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Get feedback, lots of them @nisrulz

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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

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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

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Thank You Questions? @nisrulz