Kotlin: Uma Nova Esperança

# Referências

Kotlin Reference:
http://kotlinlang.org/docs/reference/

Kotlin Blog:
http://blog.jetbrains.com/kotlin/

Using Project Kotlin for Android:
https://docs.google.com/document/d/1ReS3ep-hjxWA8kZi0YqDbEhCqTt29hG8P44aA9W0DM8/edit?pli=1

One month with Kotlin:
https://medium.com/@ademar111190/one-month-with-kotlin-2d3d9bbd7840

# Libs

Kotterknife:
https://github.com/JakeWharton/kotterknife

Anko:
https://github.com/JetBrains/anko

Kotlin Android Extensions:
http://kotlinlang.org/docs/tutorials/android-plugin.html

Transcript

1. Kotlin: Uma Nova Esperança
3. Clientes
4. Owners
6. tech@porquenao.mobi
7. Kotlin
8. Open Source JVM 100% Interoperável
9. + Plataforma - Evolução Devagar - Antiquada Java
10. Motivação Uso Industrial Moderna Design "Efetivo" Segura | Simples | Concisa
11. Alternativas Scala Groovy Dart Xtend, Clojure, etc...
12. Por que Kotlin? Desenvolvimento Ativo Próximo da versão final Funciona AGORA
13. Sintaxe
14. package mobi.porquenao.poc.kotlin import java.util.* fun main(args: Array<String>) { if (args.size() == 0) return println("First argument: ${args[0]}") } Sintaxe docs
15. val a: Int = 0 val b = 0 // Tipo Int é inferido Variáveis docs
16. // Imutável val a: Int = 0 a = 1 // Erro // Mutável var b = 0 b = 1 // OK Variáveis mutabilidade docs
17. Null Safety docs // OK var x: String = "Hi" // Erro var x: String = null // OK var x: String? = null
18. Null Safety docs var x: String? = "Hi" x.length // Erro if (x != null) { x.length // OK } x?.length // Igual acima x!!.length
19. class User { val name: String = "Luke" var surname: String = "Skywalker" fun fullName(): String { return "$name $surname" } } Class docs
20. class User(val name: String, var surname: String) { fun fullName(): String { return "$name $surname" } } val user = User("Luke", "Skywalker") println(user.fullName()) Class docs
21. Getters and Setters docs public class MainActivity : BaseActivity() { var somePreference: Boolean get() { return sharedPreferences.getBoolean("SomePreference", true) } set(value) { sharedPreferences.edit() .putBoolean("SomePreference", value) .apply() } }
22. Delegates.lazy docs val sharedPreferences by Delegates.lazy { getSharedPreferences("SharedPreference", Context.MODE_PRIVATE) } val textView: TextView by Delegates.lazy { findViewById(R.id.text) as TextView }
23. Lambdas java docs void calculate(Runnable after) { // Calcula algo after.run(); } calculate(new Runnable() { @Override public void run() { println("after"); } });
24. Lambdas docs fun calculate(after: () -> Unit) { // Calcula algo after() } calculate({ println("after") }) calculate { println("after") }
25. Lambdas docs fun sum(n1: Int, n2: Int, after: (Int) -> Unit) { // Soma algo after(n1 + n2) } sum(1, 2, { result -> println(result) }) sum(1, 2) { println(it) }
26. // SAM-type button.setOnClickListener {} // Multiple textView.addTextChangedListener(object: TextWatcher { override fun onTextChanged(s: CharSequence, start: Int, before: Int, count: Int) {} override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {} override fun afterTextChanged(s: Editable?) {} }) Lambdas android docs
27. trait Clickable { val enabled: Boolean // Propriedade fun onClick() // Método fun click() { // Implementado if (enabled) { onClick() } } } Traits docs
28. class Button : Clickable { override val enabled: Boolean = true override fun onClick() { println("Click!") } } Button().click() // "Click!" Traits docs
29. fun String.first(): Char { return this[0] } // Use val text = "Hey!" println(text.first()) //"H" Extensions docs
30. When docs fun foo(obj: Any) { when (obj) { 1 -> println("One") "Hello" -> println("Greeting") is Long -> println("Long") !is String -> println("Not a string") else -> println("Unknown") } } foo(1) // "One"
31. Performance?
32. Quase lá
33. Annotation Annotation processor não é suportado ainda: - Butterknife? - Dagger? - DBFlow? - Android APT?
34. Constantes if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { // Do something }
35. Constantes "Fix" if (Build.VERSION.SDK_INT >= 21) { // Do something }
36. - Auto-Complete um pouco mais lento - Quase versão final - Problema com permissão de arquivos - Auto-Complete de nome de variável: val user = User("Luke", "Skywalker") Outros
37. Configurando Android Studio http://kotlinlang.org/docs/tutorials/kotlin-android.html
38. Android Studio 1.2 - Preferences > Plugins - Browse repositories… - Procurar: "Kotlin" - Instalar - Reiniciar Android Studio (2015?) 1. Instalar Plugin "Kotlin"
39. 2. Configurar Gradle Plugin Editar: build.gradle buildscript { dependencies { classpath 'com.android.tools.build:gradle:1.2.2' classpath 'org.jetbrains.kotlin:kotlin-gradle-plugin:+' } }
40. 3. Configurar Dependência Editar: app/build.gradle apply plugin: 'com.android.application' apply plugin: 'kotlin-android' [...] dependencies { [...] compile 'org.jetbrains.kotlin:kotlin-stdlib:+' }
41. Acessar qualquer *.java - Code > Convert Java File to Kotlin File 4. Fim
42. Kotterknife Butterknife para Kotlin Anko Views DSL Kotlin Android Extensions Magia em findViewByid Libs
43. Telegram interno* Prezi.com interno* PorQueNão? interno* Diversos Apps em produção Desbravadores
44. Kotlin Reference Kotlin Project Kotlin Blog Kotlin Project Using Project Kotlin for Android Jake Wharton One month with Kotlin Ademar Oliveira Referências
45. Conhecimento Não Morre
46. Obrigado Mickele Moriconi @mickele Ademar Oliveira @ademar111190 https://bit.ly/kotlin-uma-nova-esperanca