Apresentação para GDG

1. Modern Android App
development
+NelsonGlauber
@nglauber
www.nglauber.com.br
Diego Nascimento
@Diego_Figue

2. We won't teaching anything in here, you can get out of
here if you want :)
The main idea is raise (and obviously discuss) the
relevant topics which are being used by the Android
Developer community around the world.
Share bad and good experiences.
Follow the Android Dev BR Slack channel
(slack.androiddevbr.org)

3. A long time ago, in a galaxy far,
far away...

4. Activity is a screen of you app…
Activity accesses the database: SQLite, Content Provider, Loaders, …
Activity accesses the web: HttpUrlConnection, AsyncTask, GSON, Loaders,
Services, …
Activity validates the fields ...
Activity had another Activities (WTF?) :O

6. Pay the consequences
Highly coupled code.
Hard to maintain and add new features.
Hard to test, consequently unstable.
Long story short… it violates all S.O.L.I.D. principles.

7. Initial Stands
for
Concept
S SRP[4] Single responsibility principle
a class should have only a single responsibility (i.e. only one potential change in the software's specification
should be able to affect the specification of the class)
O OCP[5] Open/closed principle
“software entities … should be open for extension, but closed for modification.”
L LSP[6] Liskov substitution principle
“objects in a program should be replaceable with instances of their subtypes without altering the correctness of
that program.” See also design by contract.
I ISP[7] Interface segregation principle
“many client-specific interfaces are better than one general-purpose interface.”[8]
D DIP[9] Dependency inversion principle
one should “depend upon abstractions, [not] concretions.”[8]

8. Android Blueprints
github.com/googlesamples/android-architecture

9. http://www.techyourchance.com/mvp-mvc-android-1/

10. MVP

11. MVP + Data Binding

12. MVVM + Data Binding

13. http://fernandocejas.com/2014/09/03
/architecting-android-the-clean-way/

14. MVP + Clean Architecture

15. MVP + Content Provider

16. Pros
Modularization
Separation of concerns
Facilitate tests
Avoids a "marriage" with a lib / framework

17. Cons
Increase the complexity.
Increase the number of classes.
Requires a good knowledge from the team.
Can be useless in small projects.

18. Demo time!

20. Kotlin

21. What is Kotlin?
A JVM based language developed by JetBrains (same creator of IntelliJ IDEA).
Kotlin is very intuitive and easy to learn for Java developers.
We have total integration with our daily IDE for free.

22. What's the advantages?
It’s more expressive: You can write more with much less code.
It’s safer: Kotlin is null safe.
It’s functional: Kotlin is basically an OO language, not a pure functional language.
However, it uses many concepts from functional programming.
It makes use of extension functions.
It’s highly interoperable with Java.

23. More advantages!
Full support in Android Studio
Stable
Developer community adoption is growing
Excellent documentation
Kotlin Web site: kotlinlang.org
Antonio Leiva's Book: antonioleiva.com/kotlin

26. buildscript {
ext.kotlin_version = '1.0.5-2'
ext.anko_version = '0.8.2'
repositories {
jcenter()
}
dependencies {
classpath 'com.android.tools.build:gradle:2.2.3'
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
}
}

27. apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
android {
...
sourceSets {
main.java.srcDirs += 'src/main/kotlin'
}
}
dependencies {
compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
compile "org.jetbrains.anko:anko-common:$anko_version"
...
}
...

28. Demo time!
github.com/nglauber/playground

30. Reactive Programming
Reactive = Something that will react to a stimulus / Sending of data

31. Think about it...

32. Motivation

33. Observable vs Observer

34. The one who is listening is Observer...
And the other one, who is emitting events, is subject or observable.
* Taken from the book O'Reilly Head First "Design Patterns"

35. Observable
List<String> list = Arrays.asList("BRAZIL", "USA", "JAPAN");
Observable<String> source = rx.Observable.from(list);
source.subscribe(new Action1<String>() {
@Override
public void call(String s) {
Log.d("Observable:from", s);
}
});

36. Observer
new Subscriber<News>() {
@Override
public void onCompleted() {
}
@Override
public void onError(Throwable e) {
}
@Override
public void onNext(News news) {
}
};

37. RxJava(Concepts)
Observable
Observer
Operator
Scheduler

38. Scheduler
List<String> list = Arrays.asList("BRAZIL", "USA", "JAPAN");
Observable<String> source = rx.Observable.from(list)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread());
source.subscribe(...);

39. Operator
* http://rxmarbles.com

40. Operator
* http://rxmarbles.com

41. Operator
* http://rxmarbles.com

42. Demo time!
github.com/nascimentodiego/supermarket-android

43. Questions?
+NelsonGlauber
@nglauber
www.nglauber.com.br
Diego Nascimento
@Diego_Figue