Android develop Guideline

Index: Getting start a project

- Environments - IDE of Android development - Android SDK version - Java compiler - Building system - Emulator

- Coding Style - Code Style - Use Editorconfig - Reformat code

- Workflow - Scrum

- Importance of teamwork - Mindsets - Sharing

- References Appendix: Advance for a project

- Best practices - Best resources

Training

Getting start a project

Environments

IDE of Android development

Android Studio We use Android Studio as our IDE in Android team and should stay using the newest stable version. How to Install Android studio please refer Android developer official site. Following is Android Studio configurations:

- Please turn on `Automatically check updates for Stable Channel`

Config Lint Android Level Lint We should use the default Lint configuration (e.g., origami_lint_baseline.xml) in the team. (https://developer.android.com/studio/write/lint.html) Java Level Lint: Since it can be config in Lint configuration that supported by Android we should config manually. Below those configs we should enable and make it as `warning` or `error` severity.

- Since efficiency issue please turn on `Private member access between outer and inner classes` in `Editor > Inspections` as Error severity.

- Keeping updating

Live Template Consider the consistent code style and avoid human error, and it can raise efficient while coding. We should be used to it.

For example when writing a condition of checking null object (It is not default template). Type ̀ifn` then the prompt will show up.

Select it then generate the code template and you should fill up the variables.

Hotkeys Consider the consistent code style and avoid human error, and it can raise efficient while coding. We should be used to it.

For example, Lookup the parameter hint of a method. Press ̀Command (Ctrl for Windows) + P` on a method calling.

Android SDK version Minimal SDK version: ̀Android 4.0.3 (Ice cream sandwich) API15 ̀ (but should higher than dependencies). Target SDK version: ̀Always last version ̀ (i.e., Android 7.0 (Nougat) API 24 so far) Compile SDK version: ̀Always last version ̀ (i.e., Android 7.0 (Nougat) API 24 so far) Ref: https://medium.com/google-developers/picking-your-compilesdkversion-minsdkversion-targetsdkversion-a098a0341ebd#.we0do6qn7

Java compiler Please keep your Java Development Kit (JDK) version is latest version. (For Android Library) You should also keep the java compatibility as following configuration: `Source Compatibility Version: Java Version 1.7` `Target Compatibility Version: Java Version 1.7` (For Android Application) Recommended using `Jack`: Since there some issues between Oracle’s Java compiler and Android Java compiler. And there is no reason Java compiler does optimize for Android. So in the team, we courage to use a Java compiler that able to optimize for Android and help our app to get more efficiency. Jack toolchain: >>> Jack is a new Android toolchain that compiles Java source into Android dex bytecode. It replaces the previous Android toolchain, which consists of multiple tools, such as javac, ProGuard, jarjar, and dx. (link: https://source.android.com/source/jack.html) How to enable Jack: https://developer.android.com/guide/platform/j8-jack.html#configuration ``` android { ... defaultConfig { ... jackOptions { enabled true } } compileOptions { sourceCompatibility JavaVersion.VERSION_1_8 targetCompatibility JavaVersion.VERSION_1_8 } } ```

Building system According to the default build system in Android Studio is Gradle and we need build variety of app version for different purposes. You should use Gradle as your build system in Android development. Please refer ̀Config you Build`.

Emulator Two Android emulator.

- Official Android Emulator - Genymotion Android Emulator - Personal Version in Free

Coding Style

Code Style Refer to https://source.android.com/source/code-style.html Above link that includes basic rule of coding and styling of your code. Just considering it as the common Java coding style so we also follow the rules. Here is examples, Comments: ``` /** * Constructs a new String by converting the specified array of * bytes using the platform's default character encoding. */ public String(byte[] bytes) { ... } ``` Define Fields in Standard Places: Define fields either at the top of the file or immediately before the methods that use them. ``` class Foo { String bar; void func() { String fields; }

} ``` Limit Variable Scope: ``` // Instantiate class cl, which represents some sort of Set Set s = null; try { s = (Set) cl.newInstance(); } catch(IllegalAccessException e) { throw new IllegalArgumentException(cl + " not accessible"); } catch(InstantiationException e) { throw new IllegalArgumentException(cl + " not instantiable"); } // Exercise the set s.addAll(Arrays.asList(args)); ``` ``` for (int i = 0; i < n; i++) { doSomething(i); } ``` Use Spaces for Indentation: We use four (`4`) space indents for blocks and never tabs. When in doubt, be consistent with the surrounding code. ``` for (Iterator i = c.iterator(); i.hasNext(); ) { doSomethingElse(i.next()); } ``` We use eight (`8`) space indents for line wraps, including function calls and assignments. For example, this is correct: ``` Instrument i = someLongExpression(that, wouldNotFit, on, one, line); ```

Follow Field Naming Conventions - Non-public, non-static field names start with m. (TBD) - Static field names start with s. (TBD) - Other fields start with a lower case letter. - Public static final fields (constants) are ALL_CAPS_WITH_UNDERSCORES.

``` public class MyClass { public static final int SOME_CONSTANT = 42; public int publicField; private static MyClass sSingleton; int mPackagePrivate; private int mPrivate; protected int mProtected; } ```

Use Standard Brace Style ``` class MyClass { int func() { if (something) { // ... } else if (somethingElse) { // ... } else { // ... } } } ``` ``` if (condition) body(); // bad! ```

Limit Line Length Each line of text in your code should be at most 100 characters long. While much discussion has surrounded this rule, the decision remains that 100 characters is the maximum with the following exceptions: If a comment line contains an example command or a literal URL longer than 100 characters, that line may be longer than 100 characters for ease of cut and paste. Import lines can go over the limit because humans rarely see them (this also simplifies tool writing).

Use TODO Comments ``` // TODO: Remove this code after the Url Table2 has been checked in. ```

Use Editorconfig Android Studio (IntelliJ) enable Editorconfig plugin as default and it’s supported by most of popular IDE. So we use Editorconfig as our code style configuration.

Reformat code Keep often formatting your code with,

Workflow

Scrum >>> Scrum is an iterative and incremental agile software development framework for managing product development. It defines "a flexible, holistic product development strategy where a development team works as a unit to reach a common goal", challenges assumptions of the "traditional, sequential approach" to product development, and enables teams to self-organize by encouraging physical co-location or close online collaboration of all team members, as well as daily face-to-face communication among all team members and disciplines involved. From Wikipedia Basically we do each Scrum sprint in two weeks. First, to plan Sprint. Show the progress everyday and review how the progress and determine release app or not in the second week. For more detail please see the page.

Software engineering development flow Design -> Implement -> Test

Importance of teamwork

Teamwork Mindsets - Communication with members anytime - Use project tools, i.e., Gitlab. And control the source code. - Before changing the code, you must discuss with your member who is original author of

the code if the member still be in here. - Keep discussing if you have not get to understand. - Keep finding root cause of an issue or a bug. Solve problem permanently is the most

important. - Rather found error on compile time and not happend error on runtime. - Found crashes or bugs on develop version (as early as possible) and not release

version.

Sharing Keep sharing in Android team. If you found any interesting post about Android or you want to recommend any helpful article you should feel free share it to other members. Or you can schedule a meeting to give an introduction or explanation.

References - Android Studio - Picking your SDK version - Java SE Download - Jack - Enable Java 8 Features and the Jack Toolchain - Gradle - Android Gradle - Config your Build - Android Emulator - Genymotion - Code Style for Contributors - Editorconfig

Advance for a project

Best practices - Best Practices for Performance - Best practices in Android development - Avoiding Memory Leak (Android Memory Leak Pattern)

Best resources - Must have libraries - Android Drawables - Jake Wharton’s presentations - Awesome Android UI - Awesome Android Libraries

Training Official Android Developer site is always the best training sites. Followings are the must read articles of learning developing with Android.

- Building Your First App - Supporting Different Devices - Managing the Activity Lifecycle - Building a Dynamic UI with Fragments

- Best Practices for Performance