ScalaプログラマのためのKotlin入門 ref: https://qiita.com/kmizu/items/248bcf30c44595e6d091

file0.scala

// Scala
object Main extends App {
  println("Hello, world!")
}

file1.txt

// Kotlin
fun main(args: Array<String>) {
  println("Hello, world!")
}

file10.scala

// Scala
val foo = if (bar < 42) {
  "abc"
} else {
  "xyz"
}

file11.txt

// Kotlin
val foo = if (bar < 42) {
  "abc"
} else {
  "xyz"
}

file12.scala

// Scala
for (number <- numbers) {
  println(number)
}

file13.txt

// Kotlin
for (number in numbers) {
  println(number)
}

file14.scala

// Scala
for(i <- 0 until 100) {
  println(i)
}

file15.txt

// Kotlin
for (i in 0 until 100) {
  println(i)
}

file16.scala

// Scala
for(i <- 10 to 0 by - 1) println(i)
for(i <- 0 until 100 by 2) println(i)
for(i <- 1 to 100) println(i)

file17.txt

// Kotlin
for (i in 99 downTo 0) println(i) // for (int i = 99; i >= 0; i--)
for (i in 0 until 100 step 2) println(i) // for (int i = 0; i < 100; i += 2)
for (i in 1..100) println(i) // for (int i = 1; i <= 100; i++)

file18.scala

// Scala
val s = a match {
  case 0 => "abc"
  case 1 | 2 => "def"
  case _ => "xyz"
}

file19.txt

// Kotlin
val s = when (a) {
  0 -> "abc"
  1, 2 -> "def"
  else -> "xyz"
}

file2.scala

// Scala
var s: String = "abc"
val t: String = "xyz"

file20.scala

// Scala
val foo = new Foo

file21.txt

// Kotlin
val foo = Foo()

file22.scala

// Scala
class Person(val firstName, val lastName, age: Int) {
  def fullName: String = firstName + " " + lastName
}

file23.txt

// Kotlin
class Person(val firstName: String, val lastName: String, var age: Int) {
  val fullName: String get() = firstName + " " + lastName
}

file24.scala

// Scala
val age = person.age
person.age = age + 1

file25.txt

// Kotlin
val age = person.age
person.age = age + 1

file26.txt

// Scala
class Person {
  ...

  def fullName: String = firstName + " " + lastName
}

file27.txt

// Kotlin
class Person {
  ...

  val fullName: String
    get() {
      return firstName + " " + lastName
    }
}

file28.txt

// Kotlin
class Person(val firstName: String, val lastName: String, var age: Int) {
  ...
}

file29.scala

// Scala
class Person(val firstName: String, val lastName: String, var age: Int) {
  ...
}

file3.txt

// Kotlin
var s: String = "abc"
val t: String = "xyz"

file30.scala

// Scala
class Person(val firstName: String, val lastName: String, var age: Int) {
  def this(firstName: String, lastName: String){
    this(firstName, lastName, 0)
  }

  ...
}

file31.txt

// Kotlin
class Person(val firstName: String, val lastName: String, var age: Int) {
  constructor(firstName: String, lastName: String) : this(firstName, lastName, 0) {
  }

  ...
}

file32.txt

// Kotlin
class Person(val firstName: String, val lastName: String, var age: Int = 0) {
  ...
}

file33.scala

// Scala
class Person(val firstName: String, val lastName: String, var age: Int = 0) {
  ...
}

file34.txt

// Kotlin
class Person(val firstName: String, val lastName: String) {
  ...

  // 時間経過を表すメソッド
  fun elapse(years: Int): Int {
    age += years
    return age
  }
}

file35.scala

// Scala
class Person(val firstName: String, val lastName: String) {
  ...

  // 時間経過を表すメソッド
  def elapse(years: Int): Int = {
    age += years
    age
  }
}

file36.scala

// Scala
 trait Foo {
  val bar: Int
  def baz(qux: String)
}

file37.txt

// Kotlin
interface Foo {
  val bar: Int
  fun baz(qux: String)
}

file38.txt

// Kotlin
class Box<T>(var value: T)
// {} の中に何も書かないなら↑の後の {} も不要

file39.scala

// Scala
class Box[T](var value: T)
// {} の中に何も書かないなら↑の後の {} も不要

file4.scala

// Scala
var s = "abc"
val t = "xyz"

file40.txt

// Kotlin
val cat: Box<out Cat> = Box(Cat())
val animal: Box<out Animal> = cat

val animal: Box<in Animal> = Box(Animal())
val cat: Box<in Cat> = animal

file41.scala

// Scala
val cat: Box[_ <: Cat] = Box(Cat())
val animal: Box[_ <: Animal> = cat

val animal: Box[_ >: Animal] = Box(Animal())
val cat: Box[_ >: Cat] = animal

file42.txt

// Kotlin
val a: MutableList<Int> = mutableListOf()
a.add(2)
a.add(3)
a.add(5)

val b: List<Int> = a
a.add(6)
println(b) //あ！6が入ってる！

file43.scala

// Scala
val squared = numbers.map{ x => x * x }

file44.txt

// Kotlin
val squared = numbers.map{ x -> x * x }

file45.txt

// Kotlin
import java.util.Date
import java.sql.Date as SqlDate

file46.scala

// Scala
import java.util.Date
import java.sql.{Date => SqlDate}

file5.txt

// Kotlin
var s = "abc"
val t = "xyz"

file6.scala

// Scala
var a: Int = 42
val b: Boolean = true

file7.txt

// Kotlin
var a: Int = 42
val b: Boolean = true

file8.scala

val s = a.toString()

file9.txt

val s = a.toString()