2017_11_14_Kotlin_Conf_Report_Kotlin_Types

CA.kt #4 Kotlin Conf Report
Kotlin Types
This presentation based on Kotlin Exposed Type by Svetlana Isakova in Kotlin Conf 2017.

https://cyberagent.connpass.com/event/70423/

Transcript

1. Kotlin Conf報告会 @ CA.kt #4 AAkira - Kotlin Types -
2. @_a_akira AAkira CyberAgent, Inc. Akira Aratani private lateinit var aakira : User data class User(val name: String, val twitterId: String, val githubId: String, val company: String) print("Name : ${aakira.name}”) println("Github Id : ${aakira.githubId}") print("Twitter Id : ${aakira.twitterId}") println("Company : ${aakira.company}") $ whois
3. About • 生放送配信プラットフォーム　≠ AbemaTV　≒ • M11の頃からFull Kotlinで開発 • サーバサイドも1年前からKotlinを使用
4. 私とKotlin M1 2012-04-12 M11 2015-03-19 M14 2015-10-01 1.0-beta4 2015-12-22 M13 2015-09-16 1.0 2016-02-16 1.0-RC 2016-02-04 2016-01-21 Release 2015-04 開発開始 kotlin FRESH 1.1 2017-03-01 2017-05-15 Renewal
7. Svetlana Isakova @JetBrains Kotlin in Action の著者の1人
9. Agenda • Basic types • Nullable types • Collection types
10. Agenda • Basic types • Nullable types • Collection types • Kotlin/Java types • Unit, Nothing, void • Collections →
11. Kotlin types Java types
12. Kotlin, Java Types fun foo(): Int = 1 fun bar(): Int? = 1
13. Kotlin, Java Types
14. Kotlin, Java Types public static final int foo() { return 1; } @Nullable public static final Integer bar() { return Integer.valueOf(1); }
15. Kotlin, Java Types public static final int foo() { return 1; } @Nullable public static final Integer bar() { return Integer.valueOf(1); }
16. Kotlin, Java Types Int → int Int? → java.lang.Integer
17. Kotlin, Java Types Double → int Double? → java.lang.Integer Boolean → boolean Boolean? → java.lang.Boolean
18. Kotlin, Java Types List<Int> → List<Integer> kotlin.String → java.lang.String Array<Int> → Integer[]
19. Kotlin, Java Types List<Int> → List<Integer> kotlin.String → java.lang.String Array<Int> → Integer[]
20. Kotlin, Java Types "one.two".replaceAll(".", "*")
21. Kotlin, Java Types "one.two".replaceAll(".", "*") ********
22. Kotlin, Java Types "one.two".replaceAll(".", "*") "one.two".replace(".", "*") ********
23. Kotlin, Java Types "one.two".replaceAll(".", "*") "one.two".replace(".", "*") ******** one*two
24. Kotlin, Java Types "one.two".replace(".".toRegex(), "*") "one.two".replaceAll(".", "*") "one.two".replace(".", "*") ******** one*two
25. Unit, Nothing, void
26. Unit, Nothing, void void Unit Nothing
27. Unit, Nothing, void void Unit Nothing ≠ ,
28. Unit, Nothing, void void Unit
29. Unit, Nothing, void Unit The type with only one value: the Unit object. This type corresponds to the `void` type in Java.
30. Unit, Nothing, void void Unit ⇨ 意味のない値を返す =
31. Unit, Nothing, void Nothing has no instances. You can use Nothing to represent "a value that never exists”: for example, if a function has the return type of Nothing,
 it means that it never returns (always throws an exception). Nothing
32. Unit, Nothing, void Nothing ⇨ 存在しないを表す, 値は返さない
33. Unit, Nothing, void val foo = if (bar) { 123 } else { fail() } fun fail() { throw IllegalStateException() }
34. Unit, Nothing, void val foo = if (bar) { 123 } else { fail() } fun fail(): Unit { throw IllegalStateException() }
35. Unit, Nothing, void val foo = if (bar) { 123 } else { fail() } fun fail(): Unit { throw IllegalStateException() }
36. Unit, Nothing, void val foo = if (bar) { 123 } else { fail() } fun fail(): Unit { throw IllegalStateException() } Int Unit
37. Unit, Nothing, void Int Unit Any
38. Unit, Nothing, void val foo: Any = if (bar) { 123 } else { fail() } fun fail(): Unit { throw IllegalStateException() }
39. Kotlin, Java Types Any → java.lang.Object
40. Unit, Nothing, void val foo: Any = if (bar) { 123 } else { fail() } fun fail(): Unit { throw IllegalStateException() } ⇨ fooはInt型にしたい
41. Unit, Nothing, void val foo = if (bar) { 123 } else { fail() } fun fail(): Nothing { throw IllegalStateException() }
42. Unit, Nothing, void val foo = if (bar) { 123 } else { fail() } fun fail(): Nothing { throw IllegalStateException() } Int Nothing
43. Unit, Nothing, void Int Unit Any Nothing
44. Unit, Nothing, void val foo: Int = if (bar) { 123 } else { fail() } fun fail(): Nothing { throw IllegalStateException() }
45. Unit, Nothing, void val foo: Int = if (bar) { 123 } else { fail() } fun fail(): Nothing { throw IllegalStateException() }
46. Collections
47. Collections kotlin.MutableList kotlin.List
48. Collections val mutableList = mutableListOf(1, 2, 3) val list: List<Int> = mutableList println(list) // [1, 2, 3]
49. Collections val mutableList = mutableListOf(1, 2, 3) val list: List<Int> = mutableList println(list) // [1, 2, 3] mutableList.add(4) println(list)
50. Collections val mutableList = mutableListOf(1, 2, 3) val list: List<Int> = mutableList println(list) // [1, 2, 3] mutableList.add(4) println(list) // [1, 2, 3, 4]
51. Collections ⇨ Read-only ≠ immutable mutableList.add(4) println(list) // [1, 2, 3, 4]
52. Collections fun foo(): List<Int> = listOf(1) fun bar(): MutableList<Int> = mutableListOf(1) ⇨ Decompile
53. Collections @NotNull public static final List foo() { return CollectionsKt.listOf(Integer.valueOf(1)); } @NotNull public static final List bar() { return CollectionsKt.mutableListOf(
 new Integer[]{Integer.valueOf(1)}); }
54. Collections @NotNull public static final List foo() { return CollectionsKt.listOf(Integer.valueOf(1)); } @NotNull public static final List bar() { return CollectionsKt.mutableListOf(
 new Integer[]{Integer.valueOf(1)}); }
55. Collections kotlin.MutableList kotlin.List java.util.ArrayList
56. Summary
57. Summary • Decompile to Java code • Nothing ≠ Unit, void • Read-only ≠ immutable
58. Have a nice Kotlin!