The document summarizes key points from a conference on November 9-10, 2015 about Gradle builds, Android performance, healthy code bases, and trending Android topics. It discusses optimizing Gradle builds for speed, including configuration on demand, the Gradle daemon, and avoiding expensive operations. It also covers measuring build times for different project sizes and configurations. Additional sections provide information on creating custom Gradle plugins, using data binding in Android, and new tools like Jack, Kotlin, and Eddystone beacons.

1. 9-10 novembre 2015

2. • Gradle build
• Android performance matters
• Ingredient for a healthy code base
• Barcamp
• Trending Android

4. 1. Initialization
Choose project(s) to build
2. Configuration
Execute build.gradle
Build task graph
3. Execution
Execute task chain

5. Subject application: Google IO app
• 28 libraries
• 53149 method references

6. • Configuration on Demand
• Gradle Daemon
• Newer versions of gradle
• JVM 1.8 instead of 1.6
• Avoid expensive things during configuration phase
• Don’t use dynamic dependencies (x.y.+)

8. Package cost : 1.297s
Resource change cost: 0.939s
Jave change cost 4.462s
• dex : 3.766s
• Javac : 0.876s

9. small project
dev {
multiDexEnabled true
minSdkVersion 21
}
4.633 secs
prod {} 6.599 secs
Bigger prject
dev {
multiDexEnabled true
minSdkVersion 21
}
4.416 secs
prod {
multiDexEnabled true
minSdkVersion 15
}
20.703 secs

10. Goals of a gradle plugin:
• Create a gradle task that performs a custom task
• Inject this task into the android task graph
• Parametrize this task regarding the needs of the project
• Package it and share it

11. class MyCustomTask extends DefaultTask {
@Input
def String input;
@Output
def String output;
@TaskAction
def trigger() {
// Do your stuff here
}
}

12. public class MyPlugin implements Plugin<Project> {
@Override
void apply(Project project) {
project.afterEvaluate ({
def myTask = project.tasks.create("mytask", MyCustomTask
);
myTask.input = "doStuff"
def jarTask = project.tasks.findByName("jar")
jarTask.dependsOn(myTask);
}
})
}

13. class MyTaskExtension {
def String input = null;
}

14. public class MyPlugin implements Plugin<Project> {
@Override
void apply(Project project) {
project.extensions.create("myExtension", MyTaskExtension)
project.afterEvaluate ({
// ...
myTask.input = project.myExtension.input
// ...
}
})
}

15. apply: "myPlugin"
android {
// ...
}
myExtension {
input "doStuff"
}

18. • Static analysis tools
– checkstyle
– …
• Google Play Store publishing
• Groovy library for git
• Dex count
• Sqlite Analyzer Plugin
• ...

19. • Gradle performance: https://speakerdeck.com/madisp/squeezing-
the-last-drop-of-performance-out-of-your-gradle-builds-droidcon-
paris-2015
• Build your gradle plugin https://bit.ly/gradle-plugin-next-level
• Improve android builds: https://speakerdeck.com/florianmski/level-
up-your-android-build

21. • Networking is the main battery consumer
– Less radio time means less data
– Batching to minimize radio transmission
– Prefetching by predicting what the user will do

22. • GC events eats your app framerate
– Reduce images size
– Use primitives instead of objects
– Keep an eye on your memory with management tools
(AllocationTracker, TraceView)

23. <RelativeLayout>
<ImageView/>
<LinearLayout>
<TextView/>
<TextView/>
</LinearLayout>
<ImageView/>
<ImageView/>
</RelativeLayout>
<merge>
<ImageView/>
<TextView/>
<TextView/>
<ImageView/>
<ImageView/>
</merge>
->

24. • Create your own scrolling container
– Movement tracking
– Inertia scrolling
– Scrollbars drawing
– Edge detection to get feedback

25. Performance Matter - Ran Nachmany, Google
https://youtu.be/04igNM9IpwE?list=PLn7H9CUCuXAv_kAdS0rxL1_jdxXp
FVb0r
ViewGroups - François Blavoet, Deezer
https://youtu.be/MSTG0JPOrYk?list=PLn7H9CUCuXAv_kAdS0rxL1_jdxX
pFVb0r
Advanced Scrolling - Cyril Mottier, Captain Train
https://youtu.be/N3J4ZFiR_3Q?list=PLn7H9CUCuXAv_kAdS0rxL1_jdxX
pFVb0r

28. DATA LAYER
DOMAIN LAYER
PRESENTER LAYER

29. Retrofit client DB client
ArtistRepository
• Shared preferences
• ContentProvider
• BDD

30. • Orchestrates the flow of data with use “cases”
• Offers its services to presentation layer
• Pure Java module
• No Android UI dependencies
• No dependency to external source (db,content
provider, shared preferences…)

31. ▸ public class Artist {
String displayName;
Date onTourUntil;
String uri;
String id;
String url;
String htmlUrl;
String …;
Object…;
Object …;
Object …;
}
public class ArtistViewModel {
String name;
boolean isOnTour;
}
VIEW MODEL PRESENTER VIEW

32. public interface SearchPresenter {
void searchUser(String searchItem);
void clickUser(ArtistViewModel artist);
}
public interface SearchView {
void showProgress();
void hideProgress();
void showUser(List<ArtistViewModel> artistes);
}
VIEW MODEL PRESENTER VIEW

33. public class SearchFragment extends Fragment implements SearchView {
private SearchPresenter searchPresenter;
@Override
public void showProgress() {
//...
}
@Override
public void hideProgress() {
//...
}
@Override
public void showUser(List<UserViewModel> users) {
//...
}
}

34. DATA LAYER
DOMAIN LAYER
PRESENTER LAYER
OBSERVABLE<MODEL>
OBSERVABLE<VIEWMODEL>
SUBSCRIBER<VIEWMODEL>

35. • Provides dependency: @Provides and @Module
• Request dependency: @Inject
• Link modules and injections: @Component
• Implement the singleton pattern : @Singleton

36. APPLICATION
MODULE
ACTIVITY
MODULE
FRAGMENT
MODULE
Repository
Domain
Activity
Activity
component
Application
component
Presenter
Use case

37. DATA LAYER
DOMAIN LAYER
PRESENTER LAYER
USER REPOSITORY
SEARCH USED CASE
SEARCH PRESENTER
SEARCH FRAGMENT

38. DATA LAYER
DOMAIN LAYER
PRESENTER LAYER
.JSON

39. • Choose an architecture and stick with it
• Test while your code
• Retrofit
• Dagger 2
• Rx-java
• Espresso
• Junit

40. • Clean Architecture : https://www.youtube.com/watch?v=-
oZswd1j5H0
• Slide https://speakerdeck.com/romainpiel/ingredients-for-a-healthy-
codebase
• Presentation Dagger 2 :
https://www.youtube.com/watch?v=IkTST564lA4
• slide Dagger 2 https://speakerdeck.com/jeremiemartinez/dagger-2-
back-to-basics

41. It’s a tool to :
▸ Enhance modularity
▸ Focus on business logic
▸ Reduce noise in the source code
Occurs at compile time with byte code
modification

45. • To minimize the code necessary to bind your
logic and your view
• Still in Beta
• Support library API 7

46. <data>
<variable name="user" type="com.example.User"/>
</data>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{user.firstName}”
/>

47. public class User {
public final String firstName;
public final String lastName;
public User (String firstName, String
lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
}

48. @Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MainActivityBinding binding = MainActivityBinding.inflate(getLayoutInflater());
User user = new User("Test", "User");
binding.setUser(user);
}

49. Le Data Binding sur Android - Guillaume Bernard, Koridev
https://youtu.be/fG_93vUfm5s?list=PLn7H9CUCuXAv_kAdS0rxL1_jdxXpFV
b0r
Data Binding -- Write Apps Faster (Android Dev Summit
2015)
https://youtu.be/NBbeQMOcnZ0

50. • Android Emulator
• Gives control on hardware features :
– Control the battery level
– GPS Location
– Network and call management $

52. • Jack & Jill
• Kotlin
• Eddystone

53. Java Android Compiler Kit
Jack Intermediate Library Linker
Goal is to improve incremental build
More efficient to compile compared to javac
+ dex, but still experimental

55. The swift of Android ?

56. Kotlin is compiled to Java bytecode
Possibility to use both java and Kotlin in the same
project

57. Pros
• Compile time detection of NPE with
nullable type
• Lambda
• Type inference
• Class extensions

58. Cons
• Overhead of 924 KB for runtime
• Still in beta
• Will it be adopted by the community ?

59. Beacon
• Autonomous
• Cheap (15-20€)
• Advertise data in a one way communication
Eddystone
Open beacon format

60. 3 possible messages with Eddystone
• UID
– Beacon broadcast its unique identifier
• URL
– Beacon broadcast
– Physical web
– Short range and contactless QRCode
• TLM (Telemetry)
– Maintenance (battery level, …)

62. Evolution inside the android build system
https://drive.google.com/file/d/0B1CCib0JzAOJRXZSY0c1ckZTU0E
Kotlin for Android
https://www.youtube.com/watch?v=50lASllvG3Q
Eddystone
https://www.youtube.com/watch?v=HR3X5h9xdno

64. ANDROID STUDIO 2.0

65. USABILITY (GUI)
GPS POINTS
KML
BATTERY
PHONE CALL
SMS
ROTATION
RESIZE
DRAG-DROP
FINGERPRINT