Kotlin: Uma Nova Esperança

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Clientes

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Owners

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[email protected]

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Kotlin

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Open Source JVM 100% Interoperável

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+ Plataforma - Evolução Devagar - Antiquada Java

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Motivação Uso Industrial Moderna Design "Efetivo" Segura | Simples | Concisa

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Alternativas Scala Groovy Dart Xtend, Clojure, etc...

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Por que Kotlin? Desenvolvimento Ativo Próximo da versão final Funciona AGORA

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Sintaxe

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package mobi.porquenao.poc.kotlin import java.util.* fun main(args: Array) { if (args.size() == 0) return println("First argument: ${args[0]}") } Sintaxe docs

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val a: Int = 0 val b = 0 // Tipo Int é inferido Variáveis docs

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// Imutável val a: Int = 0 a = 1 // Erro // Mutável var b = 0 b = 1 // OK Variáveis mutabilidade docs

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Null Safety docs // OK var x: String = "Hi" // Erro var x: String = null // OK var x: String? = null

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Null Safety docs var x: String? = "Hi" x.length // Erro if (x != null) { x.length // OK } x?.length // Igual acima x!!.length

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class User { val name: String = "Luke" var surname: String = "Skywalker" fun fullName(): String { return "$name $surname" } } Class docs

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class User(val name: String, var surname: String) { fun fullName(): String { return "$name $surname" } } val user = User("Luke", "Skywalker") println(user.fullName()) Class docs

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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() } }

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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 }

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Lambdas java docs void calculate(Runnable after) { // Calcula algo after.run(); } calculate(new Runnable() { @Override public void run() { println("after"); } });

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Lambdas docs fun calculate(after: () -> Unit) { // Calcula algo after() } calculate({ println("after") }) calculate { println("after") }

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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) }

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// 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

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trait Clickable { val enabled: Boolean // Propriedade fun onClick() // Método fun click() { // Implementado if (enabled) { onClick() } } } Traits docs

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class Button : Clickable { override val enabled: Boolean = true override fun onClick() { println("Click!") } } Button().click() // "Click!" Traits docs

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fun String.first(): Char { return this[0] } // Use val text = "Hey!" println(text.first()) //"H" Extensions docs

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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"

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Performance?

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Quase lá

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Annotation Annotation processor não é suportado ainda: - Butterknife? - Dagger? - DBFlow? - Android APT?

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Constantes if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { // Do something }

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Constantes "Fix" if (Build.VERSION.SDK_INT >= 21) { // Do something }

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- 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

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Configurando Android Studio http://kotlinlang.org/docs/tutorials/kotlin-android.html

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Android Studio 1.2 - Preferences > Plugins - Browse repositories… - Procurar: "Kotlin" - Instalar - Reiniciar Android Studio (2015?) 1. Instalar Plugin "Kotlin"

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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:+' } }

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3. Configurar Dependência Editar: app/build.gradle apply plugin: 'com.android.application' apply plugin: 'kotlin-android' [...] dependencies { [...] compile 'org.jetbrains.kotlin:kotlin-stdlib:+' }

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Acessar qualquer *.java - Code > Convert Java File to Kotlin File 4. Fim

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Kotterknife Butterknife para Kotlin Anko Views DSL Kotlin Android Extensions Magia em findViewByid Libs

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Telegram interno* Prezi.com interno* PorQueNão? interno* Diversos Apps em produção Desbravadores

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Kotlin Reference Kotlin Project Kotlin Blog Kotlin Project Using Project Kotlin for Android Jake Wharton One month with Kotlin Ademar Oliveira Referências

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Conhecimento Não Morre

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Obrigado Mickele Moriconi @mickele Ademar Oliveira @ademar111190 https://bit.ly/kotlin-uma-nova-esperanca