Let's Try Kotlin
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The document discusses getting started with learning and using the Kotlin programming language. It provides an introduction to the author and their experience with Kotlin. Key reasons why Kotlin is a good choice are that it is concise, safe, expressive, interoperable with Java, and supports multiplatform development. Methods for learning Kotlin include books, videos, programming practice, and using the Kotlin Playground. Areas where Kotlin can be enjoyed include Android app development, Spring applications, and web development with tools like Visual Studio Code. The document encourages trying out Kotlin.
![Why Kotlin?: Expressive
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Let's Try Kotlin
- 1. Let’s Try Kotlin!! Try English LT! for engineers 2023-01-07（Sat） へー／heisy（SASAKURA Hideyuki）
- 2. My Profile ● へー／heisy（SASAKURA Hideyuki） ○ Twitter : @heisy ● IT Engineer ● Likes ○ AWS ○ Java ○ Kotlin ○ DDD / TDD ○ Bouldering & Climbing ○ Drinking 🍶🍶🍶
- 3. Introduction KotlinFest2022 on 10th Dec 2022. I was Staff. But…
- 4. Introduction I don’t touch Kotlin for several years 😭
- 5. Introduction So I’m Kotlin Lover if not much of one, I restart Kotlin this year !! As beginner…😓
- 6. Agenda ● Why Kotlin? ● How learn Kotlin ? ● More enjoy coding with Kotlin
- 7. Why Kotlin? ● Concise ● Safe ● Expressive ● Interoperable ● Multiplatform
- 8. Why Kotlin?: Concise data class Employee( val name: String, val email: String, val company: String ) // + automatically generated equals(), hashCode(), toString(), and copy() object MyCompany { // A singleton const val name: String = "MyCompany" } fun main() { // Function at the top level val employee = Employee("Alice", // No `new` keyword "alice@mycompany.com", MyCompany.name) println(employee) }
- 9. Why Kotlin?: Safe fun reply(condition: Boolean): String? = // Nullability is part of Kotlin’s type system if (condition) "I'm fine" else null fun error(): Nothing = // Always throw an exception throw IllegalStateException("Shouldn't be here") fun main() { val condition = true // Try replacing `true` with `false` and run the sample! val message = reply(condition) // The result is nullable // println(message.uppercase()) // This line doesn't compile println(message?.replace("fine", "okay")) // Access a nullable value in a safe manner if (message != null) { // If you check that the type is right, println(message.uppercase()) // the compiler will smart-cast it for you } val nonNull: String = // If the null-case throws an error, reply(condition = true) ?: error() // Kotlin can infer that the result is non-null println(nonNull) }
- 10. Why Kotlin?: Expressive val map = mapOf(1 to "one", 2 to "two") for ((k, v) in map) { // Traverse a map or a list of pairs println("$k -> $v") }
- 11. Why Kotlin?: Expressive fun obtainKnowledge() = Pair("The Answer", 42) // Single-expression functions val (description, answer) = obtainKnowledge() // Destructure into a pair of two variables println("$description: $answer") getText()?.let { // Apply an action to a nullable expression sendEmailTo("alice@example.com", it) // if it’s not null }
- 12. Why Kotlin?: Expressive createEmptyWindow() .apply { // Configure properties of an object width = 300 height = 200 isVisible = true }.also { w -> // Perform an additional operation on a call chain showWindow(w) } val fixedIssue = issueById["13456"] ?.takeIf { it.status == Status.FIXED } // Use the value only if the condition is true println(fixedIssue)
- 13. Why Kotlin?: Interoperable Kotlin use JVM library or framework. Call Kotlin code from Java without an issue.
- 14. Why Kotlin?: Multiplatform Kotlin is sharing same code across Android, iOS, Web apps, JS.
- 15. How learn Kotlin? Kotlin learning method is blow. ● Books ● Session/Training movies ● Programing
- 16. How learn Kotlin? Kotlin Playground is one of best tools to learn Kotlin.
- 17. How learn Kotlin? You will find it easy to get samples from play.kotlinlang.org.
- 18. How learn Kotlin? Kotlin has Coroutines. It's exciting!
- 19. More enjoy coding with Kotlin We enjoy Kotlin as follows. ● Android apps ● Spring etc…
- 20. More enjoy coding with Kotlin Android mobile development has been Kotlin-first.
- 21. More enjoy coding with Kotlin Spring support building web application by Kotlin.
- 22. More enjoy coding with Kotlin Visual Studio Code support building Kotlin Web application.
- 23. So Let’s Try Kotlin !!
- 24. End
- 25. Thank you ! Have a nice Kotlin!