![変数
val foo: String = "foo"
// foo = null // Null safety
// 型推論
val num = 1
// val cannot be reassigned
// num1 = 123
var num2 = 2
num2 = 123
val li = listOf(1, 2, 3)
// li[2] = 4 // error
val ml = mutableListOf(4, 5, 6)
ml[2] = 7
8](https://image.slidesharecdn.com/kotlin-handson-180810141038/85/Kotlin-handson-8-320.jpg)
Kotlin handson
- 7. HelloWorld File‑>New‑>KotlinFile/Class fun main(args: Array<String>) { println("Hello World") } 7
- 8. 変数 val foo: String = "foo" // foo = null // Null safety // 型推論 val num = 1 // val cannot be reassigned // num1 = 123 var num2 = 2 num2 = 123 val li = listOf(1, 2, 3) // li[2] = 4 // error val ml = mutableListOf(4, 5, 6) ml[2] = 7 8
- 9. FizzBuzz fun fizzBuzz(n: Int) = when { n % 15 == 0 -> println("FizzBuzz") n % 3 == 0 -> println("Fizz") n % 5 == 0 -> println("Buzz") else -> println(n) } fun main(args: Array<String>) { (1..15).forEach { fizzBuzz(it) } } 9
- 10. データクラス data class User(val name: String, var age: Int = 0) fun main(args: Array<String>) { val taro = User("taro") taro.age = 12 println(taro.hashCode()) val jiro = taro.copy(name = "jiro") println(jiro.toString()) } 10
- 13. HelloWorld×SpringBoot @SpringBootApplication class DemoApplication fun main(args: Array<String>) { runApplication<HandsonApplication>(*args) } @RestController class HelloController { @GetMapping("/hello") fun hello() = "Hello, World!" } 13
- 14. Fin 14