JVM言語のかわいいルーキー Kotlinの紹介

DevLOVE現場甲子園2014 東日本大会で発表したときのスライドです。

Transcript

1. +7.ݴޠͷ͔Θ͍͍ϧʔΩʔ
   Kotlinͷ঺հ 
   %FW-07&ݱ৔ߕࢠԂ
   ౦೔ຊେձ
   ճද
   ٕτϥοΫ
   ! ೔ຊ,PUMJOϢʔβάϧʔϓ
 ௕ᖒ
   ଠ࿠
2. ΞδΣϯμ  ࣗݾ঺հ
    ,PUMJOͱ͸
    ,PUMJOͰ̋̋
    ·ͱΊ
3. 
   ࣗݾ঺հ
4. جຊ৘ใ w ௕ᖒ
   ଠ࿠
   !OHTX@UBSP
   w ιϑτ΢ΣΞΤϯδχΞ
   w ࣗশ,PUMJOΤόϯδΣϦετ
   w "OESPJE޷͖ͩΑ
5. ΅͘ͱ,PUMJO 
   ,PUMJOͱग़ձ͏
   
   ղઆαΠτΛ্ཱͪ͛Δ
   
   ҰਓΞυϕϯτΧϨϯμʔʹ௅ઓ
   
   ೔ܦιϑτ΢ΤΞʹ,PUMJOهࣄΛدߘ
   
   ୈճ͔Θ͍͍,PUMJOษڧձΛ։࠵
   
   ++6(
   $$$Ͱ+7.ݴޠύωϧσΟεΧογϣϯ
   
   ΞυϕϯτΧϨϯμʔΛ࣮ࢪ
   
   ୈճ͔Θ͍͍,PUMJOษڧձΛ։࠵
   
6. 
   ,PUMJOͱ͸
7. ,PUMJOͱ͸ w ϓϩάϥϛϯάݴޠ
   w +BWB7.্Ͱಈ͘+BWBόΠτίʔυʹί ϯύΠϧ͞ΕΔ
   w +FU#SBJOTΛத৺ʹ։ൃ͞Ε͍ͯΔ044
   w ೥ʹൃදɺݱࡏWFS
   
8. ͳͥ,PUMJOͳͷ͔ w δϟό͸ͪΐͬͱʜ
   w 4DBMB͸ػೳ͕ଟͯ͘೉͍͠
   w (SPPWZ͸ಈతͰ೉͍͠
   w ͪΐ͏Ͳ͍͍ͱ͜Ζ͕ཉ͍͠ʂ
9. ,PUMJO͕໨ࢦ͢ͱ͜Ζ w γϯϓϧ
   w ҆શ
   w ଎͍ ͬ͘͟Γݴ͏ͱ
10. ,PUMJOͷಛ௃ w γϯϓϧ
    w ܕ҆શɺ/VMM҆શ
    w +7.Ͱಈ͘
    w +BWB4DSJQUʹ΋ίϯύΠϧՄೳ
    w ੩తܕ෇͚
    w ΦϒδΣΫτࢦ޲
    w ؔ਺ܕϓϩάϥϛϯά
11. 
    ,PUMJOͰ̋̋
12. ͦͷ
    ,PUMJOͰ)FMMP8PSME
13. )FMMP8PSME package hello fun main(args : Array<String>) { println("Hello, world!") }
14. )FMMP8PSME package hello fun main(args : Array<String>) { println("Hello, world!") } ύοέʔδ௚Լʹ
    ؔ਺͕ஔ͚Δ ΤϯτϦϙΠϯτ͸
    NBJOؔ਺
15. )FMMP8PSME package hello fun main(args : Array<String>) { println("Hello, world!") } ม਺ͷܕ͕ޙஔ ഑ྻ͕
    δΣωϦΫε
16. )FMMP8PSME package hello fun main(args : Array<String>) { println("Hello, world!") } ηϛίϩϯ
    ෆཁ
17. ͦͷ
    ,PUMJOͰ'J[[#V[[
18. 'J[[#V[[ for (i in 1..100) { val result = if (i % 15 == 0) "FizzBuzz" else if (i % 3 == 0) "Fizz" else if (i % 5 == 0) "Buzz" else i.toString() println(result) }
19. 'J[[#V[[ for (i in 1..100) { val result = if (i % 15 == 0) "FizzBuzz" else if (i % 3 == 0) "Fizz" else if (i % 5 == 0) "Buzz" else i.toString() println(result) } +BWBͰ͍͏ͱ͜Ζͷ
    ֦ுGPSจͷΈ 3BOHF
    ΦϒδΣΫτ
20. 'J[[#V[[ for (i in 1..100) { val result = if (i % 15 == 0) "FizzBuzz" else if (i % 3 == 0) "Fizz" else if (i % 5 == 0) "Buzz" else i.toString() println(result) } ܕਪ࿦
    pOBM
    4USJOH
    SFTVMU
    
    ʜ
21. 'J[[#V[[ for (i in 1..100) { val result = if (i % 15 == 0) "FizzBuzz" else if (i % 3 == 0) "Fizz" else if (i % 5 == 0) "Buzz" else i.toString() println(result) } JGFMTF͸ࣜ
    ஋Λฦ͢
22. ͦͷ
    ,PUMJOͰؔ਺ܕϓϩάϥϛϯά
23. ؔ਺͕pSTUDMBTT val add = { (a: Int, b: Int) -> a + b } ! val add2 = add add2(3, 4) / / => 7
24. ؔ਺͕pSTUDMBTT val add = { (a: Int, b: Int) -> a + b } ! val add2 = add add2(3, 4) / / => 7 ؔ਺ϦςϥϧͰ
    ؔ਺Λੜ੒ͯ͠
    ม਺ʹ୅ೖ ී௨ͷม਺ͷ
    Α͏ʹѻ͑Δ
25. ؔ਺͕pSTUDMBTT val add = { (a: Int, b: Int) -> a + b } ! val add2 = add add2(3, 4) / / => 7 ී௨ͷؔ਺ݺͼग़͠
    ͷΑ͏ʹهड़Ͱ͖Δ
26. ߴ֊ؔ਺ val predicate = { (i: Int) -> i % 2 != 0 } list.filter(predicate)
27. ߴ֊ؔ਺ val predicate = { (i: Int) -> i % 2 != 0 } list.filter(predicate) Ҿ਺͕ح਺ͳΒ
    USVFͱͳΔड़ޠ ड़ޠͰ΋ͬͯ
    ϑΟϧλϦϯά
28. ؔ਺Ϧςϥϧ
    ϥϜμࣜ list.filter({ (i: Int) -> i % 2 != 0 })
29. ؔ਺Ϧςϥϧ
    ϥϜμࣜ list.filter { it % 2 != 0 } list.filter({ (i: Int) -> i % 2 != 0 })
30. ؔ਺Ϧςϥϧ
    ϥϜμࣜ list.filter { it % 2 != 0 } list.filter({ (i: Int) -> i % 2 != 0 }) ҉໧ͷม਺
    JU
    ܕ͸ਪ࿦͞ΕΔ
31. ίϨΫγϣϯܥϝιου pMUFS
    ཁૉΛϑΟϧλ͢Δ
    DPVOU
    ৚݅ʹ߹͏ཁૉͷ਺Λฦ͢
    pOE
    ৚݅ʹ߹͏࠷ॳͷཁૉΛฦ͢
    NBQ
    ֤ཁૉΛࣸͨ͠ίϨΫγϣϯΛฦ͢
    qBU.BQ
    NBQޙʹϑϥοτʹ͢Δ
    BMM
    ͢΂ͯͷཁૉ͕৚݅ʹ߹͏ͳΒUSVF
    BOZ
    ͍ͣΕ͔ͷཁૉ͕৚݅ʹ߹͏ͳΒUSVF
    GPME
    શཁૉΛ૸ࠪͯͭ͠ͷ஋ʹ·ͱΊΔ
32. ΠϯϥΠϯؔ਺ val r = list.filter { it % 2 != 0 } inline fun filter(p: (T)->Boolean) { … }
33. ΠϯϥΠϯؔ਺ val r = list.filter { it % 2 != 0 } 
    ྫ͑͹
    val list_ = arrayListOf<T>() for(e in list) if(e % 2 != 0) list_.add(e) val r = list_ ΠϯϥΠϯల։͞ΕΔ
    Φʔόϔου௿ݮ inline fun filter(p: (T)->Boolean) { … }
34. ຤ඌݺग़͠࠷దԽ 5$0 tailRecursive fun sum(ints: List<Int>, s: Int = 0): Int = if(ints.none()) s else sum(ints.tail, s + ints.first()) UBJM3FDVSTJWFΞϊςʔγϣϯ
    ຤ඌͷ࠶ؼݺग़͠Λɺϧʔϓͱͯ͠
    ίϯύΠϧͯ͘͠ΕΔ
35. ͦͷ
    ,PUMJOͰΦϒδΣΫτࢦ޲
36. Ϋϥε class Greeter ! val greeter = Greeter()
37. Ϋϥε class Greeter ! val greeter = Greeter() ࠷খͷ
    Ϋϥεఆٛ ΠϯελϯεԽ
    OFXෆཁ
38. ϝιου class Greeter { fun greet() { println("Hello") } }
39. ϝιου class Greeter { fun greet() { println("Hello") } } ݺͼग़͠ํ
    HSFFUFSHSFFU
40. ϓϩύςΟ class User(name: String) { var name: String = name } ! val user = User("Taro") user.name / / => "Taro"
41. ϓϩύςΟ class User(name: String) { var name: String = name } ! val user = User("Taro") user.name / / => "Taro" ίϯετϥΫλ ϓϩύςΟ
42. ϓϩύςΟ class User(name: String) { var name: String = name } ! val user = User("Taro") user.name / / => "Taro" ϑΟʔϧυʹ௚઀
    ΞΫηε͍ͯ͠Δ෩
43. ΞΫηα class User(name: String) { var name: String = name set(name: String) {$name = name } get(): String = $name }
44. ΞΫηα class User(name: String) { var name: String = name set(name: String) {$name = name } get(): String = $name } ϓϩύςΟ໊
    CBDLJOH
    pFME
45. %FMFHBUFE
    1SPQFSUZ class User(name: String) { val name: String by Decorator(name) } ! class Decorator(val str: String) { fun get(thisRef: Any, prop:PropertyMetadata): String = "˒$str˒" }
46. %FMFHBUFE
    1SPQFSUZ class User(name: String) { val name: String by Decorator(name) } ! class Decorator(val str: String) { fun get(thisRef: Any, prop:PropertyMetadata): String = "˒$str˒" } 6TFSOBNF΁ͷ
    ΞΫηε͕ҕৡ͞ΕΔ
47. ܧঝ open class Foo { fun foo(): String = "foo" } ! class Bar: Foo() ! Bar().foo() / / => foo
48. ܧঝ open class Foo { fun foo(): String = "foo" } ! class Bar: Foo() ! Bar().foo() / / => foo PQFOඞਢ
    σϑΥϧτͰ͸ܧঝෆՄ &⒎FDUJWF
    +BWB
    ߲໨
    ܧঝͷͨΊʹઃܭٴͼจॻԽ͢ΔɺͰͳ͚ Ε͹ܧঝΛېࢭ͢Δ
49. τϨΠτ trait A { fun hoge() = "A" fun fuga(): String } ! class Sample: A { override fun fuga() = "Sample" }
50. τϨΠτ trait Hoge { fun hoge() = "A" fun fuga(): String } ! class Sample: Hoge { override fun fuga() = "Sample" } GVHB ͸࣮૷ඞਢ PWFSSJEFΞϊςʔγϣϯ
51. τϨΠτ trait Hoge { fun hoge() = "A" fun fuga(): String } ! class Sample: Hoge { override fun fuga() = "Sample" } σϑΥϧτ࣮૷Λ
    ࣋ͯΔ
52. ଟॏܧঝ trait A { fun a() = "A" } trait B { fun a() = "B" } ! class C: A, B { override fun a() = super<A>.a() }
53. ଟॏܧঝ trait A { fun a() = "A" } trait B { fun a() = "B" } ! class C: A, B { override fun a() = super<A>.a() } ಉ໊͡લͷ࣮૷Λ
    ଟॏܧঝ ಉ໊͡લͷ࣮૷Λ
    ଟॏܧঝ
54. ҕৡ class Data(val value: String) ! trait Dao { fun save(data: Data) } ! class Service(dao: Dao): Dao by dao { fun createData(value: String) { val data = Data(value) save(data) } }
55. ҕৡ class Data(val value: String) ! trait Dao { fun save(data: Data) } ! class Service(dao: Dao): Dao by dao { fun createData(value: String) { val data = Data(value) save(data) } } ܕ͸ܧঝ͢Δʂ
    ࣮૷͸ҕৡ͢Δʂ
56. ͦͷ
    ,PUMJOͰ%4-
57. ͦͷ
    ,PUMJOͰ%4- %4-Ͱ࢖͑Δ
    ߏจ౶ҥͳͲ
58. தஔݺग़͠
    JOpY
    DBMM "Kotlin".compareTo("Java") "Kotlin" compareTo "Java"
59. ֦ுϝιου fun String.hello() { println("Hello, $this") } ! "World".hello()
60. ֦ுϓϩύςΟ val String.upperCaseNum: Int get() = filter { it.isUpperCase() }.size ! "JavaCoffee".upperCaseNum / / => 2
61. ԋࢉࢠΦʔόϩʔυ class MyInt(val value: Int) { fun plus(that: MyInt): MyInt = MyInt(this.value + that.value) } ! MyInt(5) + MyInt(3) / / => MyInt(8)
62. Ԡ༻ྫ 5.hours - 42.minuts
63. Ԡ༻ྫ 5.hours - 42.minuts ֦ுϓϩύςΟ ֦ுϓϩύςΟ ԋࢉࢠ
    Φʔόϩʔυ
64. ͦͷ
    ,PUMJOͰ"OESPJEΞϓϦ
65.  "OESPJE
    4UVEJPͰϓϩδΣΫτ࡞੒
     TSDNBJOKBWBʹLUϑΝΠϧΛ࡞੒
     ΫϦοΫˠ
     "OESPJE
    4UVEJP͕ࣗಈͰ͍Ζ͍Ζઃ ఆͯ͘͠ΕΔ "OESPJE
    4UVEJPͰ࢝ΊΔ "OESPJE
    4UVEJP
    
    ,PUMJO
    1MVHJO
    
66. ,PUMJOͰ୯७ͳ"DUJWJUZ class MainActivity : Activity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) } }
67. ϏϡʔΛर͍͍ͬͯ͜ͱ͢Δ val button: Button? = findViewById(R.id.button) if (button != null) { button.setText("Click me") }
68. ϏϡʔΛर͍͍ͬͯ͜ͱ͢Δ val button: Button? = findViewById(R.id.button) if (button != null) { button.setText("Click me") } ܕ
    
    
69. /VMM҆શ val n: Int = null ,PUMJOͰ͸σϑΥϧτͰOVMMېࢭ ίϯύΠϧΤϥʔ
70. /VMM҆શ val n: Int? = null OVMMΛड͚औΔʹ͸
    OVMMڐ༰ܕͰ͋Δ͜ͱΛ໌ࣔ͢Δ
71. /VMM҆શ val a: Int = null / / OK val b: Int? = null / / NG b.toString() / / NG if(b != null) b.toString() / / OK b?.toString() / / OK
72. /VMM҆શ val a: Int = null / / OK val b: Int? = null / / NG b.toString() / / NG if(b != null) b.toString() / / OK b?.toString() / / OK if (b != null) b.toString() else null
73. ϏϡʔΛर͍͍ͬͯ͜ͱ͢Δ val button: Button? = findViewById(R.id.button) ! button?.setText("Click me") / / if (button != null) { / / button.setText("Click me") / / }
74. 4JOHMF
    "CTUSBDU
    .FUIPE button.setOnClickListener { Log.d(TAG, "Clicked") } button.setOnClickListener(object: OnClickListener { override fun onClick(v: View) { Log.d(TAG, "Clicked") } })
75. 4JOHMF
    "CTUSBDU
    .FUIPE button.setOnClickListener { Log.d(TAG, "Clicked") } button.setOnClickListener(object: OnClickListener { override fun onClick(v: View) { Log.d(TAG, "Clicked") } }) PCKFDUࣜ
    ಗ໊Ϋϥε
76. 4JOHMF
    "CTUSBDU
    .FUIPE button.setOnClickListener { Log.d(TAG, "Clicked") } button.setOnClickListener(object: OnClickListener { override fun onClick(v: View) { Log.d(TAG, "Clicked") } }) ந৅ϝιουͭͷΈ
    ؔ਺ϦςϥϧͰදهͰ͖Δ
77. 7JFXͷ*OKFDUܥπʔϧ w "OESPJE"OOPUBUJPOTͳͲͷ"15
    
    
    
    
    
    
    
    ,PUMJOͰ͸࢖͑ͳ͍
    w 3PCP(VJDFͳͲͷϦϑϨΫγϣϯܥ
    
    
    
    
    
    
    
    ,PUMJOͰ΋࢖͑Δ
78. %FMFHBUFE
    1SPQFSUZ࠶ͼ class User(name: String) { val name: String by Decorator(name) } ! class Decorator(val str: String) { fun get(thisRef: Any, prop:PropertyMetadata): String = "˒$str˒" }
79. Ԡ༻ྫ
    7JFXͷ*OKFDU class MainActivity: Activity() { val submitButton: Button by injector() ! fun onCreate(savedInstanceState: Bundle?) { submitButton.setOnClickListener(::submit) } }
80. ͓·͚
    ,PUMJOͰ̋̋
81. ,PUMJOͰ#%%ελΠϧͷςετ class TaxCalculatorSpecs: Spek() {{ ! given("Tax rate calculator with default locale settings") { val taxRateCalculator = TaxRateCalculator() on("calculating the rate for an income of 200 and an average change of 10 per semester") { val value = taxRateCalculator.calculateRate(200, 10) it("should result in a value of 300") { assertEquals(300, value) } } } }} ςετϑϨʔϜϫʔΫ! Spek http://jetbrains.github.io/spek/ΑΓҾ༻
82. ,PUMJOͰ8FCΞϓϦ w ΋ͪΖΜී௨ͷαʔϒϨοτΛॻ͚Δ
    w 8BTBCJ
    4JOBUSBΠϯεύΠΞܥ
    w ,BSB
    )5.-
    $44΋,PUMJOͰ
    w /PEFLU
    /PEFKTͬΆ͍΍ͭ
83. ,PUMJOͰ8FCΞϓϦ w ΋ͪΖΜී௨ͷαʔϒϨοτΛॻ͚Δ
    w 8BTBCJ
    4JOBUSBΠϯεύΠΞܥ
    w ,BSB
    )5.-
    $44΋,PUMJOͰ
    w /PEFLU
    /PEFKTͬΆ͍΍ͭ 8BTBCJҎ֎͸
    ΄΅ߋ৽͞Εͯͳ͍
84. ,PUMJOͰ+BWB4DSJQU w +BWB4DSJQU΁ͷίϯύΠϧՄೳ
    https://speakerdeck.com/ntaro/tian-xia- altjswu-dao-hui-kotlin-number- tenka1altjs ఱԼҰaltJS෢ಓձ Kotlin
85. ͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠