/kotlin

Kotlin Tutorial

Primary LanguageKotlin

Kotlin触ってみた

学習内容

  • Hello World
    • println: 文字列表示後に改行される
    • print: 文字列を表示する
  • variables
    • val: read-only
    • var: mutable
    • print variable:
      • println("it's $variable")
      • println("it's ${variable + 1}")
    • 型推論あり
  • Basic types
  • Collections
    • each collection type can be mutable or read-only
    • casting is supported
  • Control flow
    • if, when
    • range
      • 1..4, 1..<4, 4 downTo 1, 1..5 step 2
    • for, while(do-while)
  • Functions
  • Classes
  • Null safety

Basic Types

For more information on basic types and their properties, see Basic types.

Category Basic types
Integers Byte, Short, Int, Long
Unsigned integers UByte, UShort, UInt, ULong
Floating-point numbers Float, Double
Booleans Boolean
Characters Char
Strings String

Collections

Collection Type Description
Lists Ordered collections of items
Sets Unique unordered collections of items
Maps Sets of key-value pairs where keys are unique and map to only one value

casting

To prevent unwanted modifications, you can obtain read-only views of mutable lists by assigning them to a List:

val shapes: MutableList<String> = mutableListOf("triangle", "square", "circle")
val shapesLocked: List<String> = shapes

参考