Types de base Kotlin : Int, Double, Boolean, Char

Le système de types de Kotlin

Types entiers

val age: Int = 25
val population: Long = 8_000_000_000L
val score: Short = 100
val flags: Byte = 0b00001111

Types à virgule flottante

val pi: Double = 3.14159
val gravity: Float = 9.81f
val result = pi * 2  // Double arithmetic

Type booléen

val isOnline: Boolean = true
val isEmpty = false
println(!isOnline)           // false
println(isOnline && !isEmpty) // true

Type caractère

val letter: Char = 'A'
val digit: Char = '7'
val emoji: Char = '\u2764'  // heart
println(letter.code)         // 65 (ASCII)

L’inférence de type en pratique

val count = 10        // Int
val ratio = 0.75      // Double
val active = true     // Boolean
val initial = 'K'     // Char

Traits de soulignement numériques pour la lisibilité

val million = 1_000_000
val hex = 0xFF_AA_BB
val binary = 0b1010_1010
println(million) // 1000000

Conversion des nombres

val x: Int = 42
val y: Long = x.toLong()    // explicit
val z: Double = x.toDouble()
println("$y $z")

String n’est pas un type primitif

val name: String = "Kotlin"
println(name.length)         // 6
println(name.uppercase())    // KOTLIN
println(name[0])             // K (Char)

Any, Nothing et Unit

fun greet(): Unit { println("Hi") }
fun fail(): Nothing { throw Exception("!!") }
val x: Any = 42  // Any accepts anything

Vérifier les types avec is

val obj: Any = "Hello"
if (obj is String) {
    println(obj.length) // smart cast: no cast needed!
}

Vérification rapide

Récapitulatif