KotlinのDelegated Propertiesを活用してAndroidアプリ開発をもっと便利にする

Kotlinには委譲プロパティ（Delegetaed proprties）という仕組みがあります。
標準ライブラリのlazyや、AndroidXのActivityやFragmentに実装されているviewModelなどで普段からあまり意識せずに利用している方も多いと思います。
本セッションでは、標準ライブラリに含まれている委譲プロパティ、および拙作のライブラリであるKotprefなどの事例を交えながら、委譲プロパティの仕組み、Kotlinでの実現方法、活用事例や自作する際の方法などをお話します。

本セッションに含まれる内容
- KotlinのDelegated Propertiesとは
- Delegated Propertiesの仕組み
- 標準ライブラリで提供されるDelegated Properties
- 作って見ることでより深く理解する
- Tips

Transcript

1. ,PUMJOͷ%FMFHBUFE
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2. ࣗݾ঺հ • ઍ༿ོ༤
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3. ໨࣍ 
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4. %FMFHBUFE
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5. %FMFHBUFE
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6. %FMFHBUFE
   1SPQFSUJFTͱ͸ class DelegateSample { var myProp: String by MyDelegate() var someProp: String by someDelegate() private fun someDelegate() = SomeDelegate() }
7. %FMFHBUFE
   1SPQFSUJFTͱ͸ class DelegateSample { var myProp: String by MyDelegate() var someProp: String by someDelegate() private fun someDelegate() = SomeDelegate() } CZͷޙʹҕৡઌͷ
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8. %FMFHBUFE
   1SPQFSUJFTͱ͸ class DelegateSample { var myProp: String by MyDelegate() var someProp: String by someDelegate() private fun someDelegate() = SomeDelegate() } ҕৡઌΦϒδΣΫτΛ
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9. %FMFHBUFE
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10. %FMFHBUFE
    1SPQFSUJFTͱ͸ class DelegateSample { var myProp: String by MyDelegate() }
11. %FMFHBUFE
    1SPQFSUJFTͱ͸ class DelegateSample { private val myProp$delegate = MyDelegate() var myProp: String get() = myProp$delegate.getValue(this, this::myProp) set(value: String) = myProp$delegate.setValue(this, this::myProp, value) }
12. %FMFHBUFE
    1SPQFSUJFTͱ͸ class DelegateSample { private val myProp$delegate = MyDelegate() var myProp: String get() = myProp$delegate.getValue(this, this::myProp) set(value: String) = myProp$delegate.setValue(this, this::myProp, value) } ҕৡઌͷΦϒδΣΫτΛQSJWBUFͳ
    ϓϩύςΟͱͯ͠อ࣋
13. %FMFHBUFE
    1SPQFSUJFTͱ͸ class DelegateSample { private val myProp$delegate = MyDelegate() var myProp: String get() = myProp$delegate.getValue(this, this::myProp) set(value: String) = myProp$delegate.setValue(this, this::myProp, value) } ҕৡઌΦϒδΣΫτ͕
    HFUͷॲཧΛ͢Δ
14. %FMFHBUFE
    1SPQFSUJFTͱ͸ class DelegateSample { private val myProp$delegate = MyDelegate() var myProp: String get() = myProp$delegate.getValue(this, this::myProp) set(value: String) = myProp$delegate.setValue(this, this::myProp, value) } ಉ༷ʹҕৡઌΦϒδΣΫτ͕
    TFUͷॲཧΛ͢Δ
15. %FMFHBUFE
    1SPQFSUJFTͱ͸ • ৄࡉͳ࢓૊Έ΍࣮૷ํ๏͸ޙ൒ʹ
16. ඪ४ϥΠϒϥϦͰఏڙ͞ΕΔ %FMFHBUFE
    1SPQFSUJFT
17. TUEMJCͷ%FMFHBUFE
    1SPQFSUJFT • MB[Z
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    • %FMFHBUFTPCTFSWBCMFWFUPBCMF
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18. MB[Z
19. MB[Z • ϓϩύςΟͷॳظԽΛ࠷ॳͷࢀর·Ͱ஗Ԇ val lazyProperty: String by lazy { "initialized at ${System.currentTimeMillis()}" }
20. MB[Z • ϓϩύςΟͷॳظԽΛ࠷ॳͷࢀর·Ͱ஗Ԇ val lazyProperty: String by lazy { "initialized at ${System.currentTimeMillis()}" } println(System.currentTimeMillis()) // 1581485501007 delay(500)
21. MB[Z • ϓϩύςΟͷॳظԽΛ࠷ॳͷࢀর·Ͱ஗Ԇ val lazyProperty: String by lazy { "initialized at ${System.currentTimeMillis()}" } println(System.currentTimeMillis()) // 1581485501007 delay(500) println(lazyProperty) // initialized at 1581485501514 ࠷ॳͷࢀর࣌ʹϒϩοΫ͕࣮ߦ͞Ε
    ϓϩύςΟ͕ॳظԽ͞ΕΔ NT
22. MB[Z • ϓϩύςΟͷॳظԽΛ࠷ॳͷࢀর·Ͱ஗Ԇ val lazyProperty: String by lazy { "initialized at ${System.currentTimeMillis()}" } println(System.currentTimeMillis()) // 1581485501007 delay(500) println(lazyProperty) // initialized at 1581485501514 delay(500) println(lazyProperty)
23. MB[Z • ϓϩύςΟͷॳظԽΛ࠷ॳͷࢀর·Ͱ஗Ԇ val lazyProperty: String by lazy { "initialized at ${System.currentTimeMillis()}" } println(System.currentTimeMillis()) // 1581485501007 delay(500) println(lazyProperty) // initialized at 1581485501514 delay(500) println(lazyProperty) // initialized at 1581485501514 ճ໨Ҏ߱ͷΞΫηεͰ͸࠷ॳʹ
    ࣮ߦͨ͠ͱ͖ͷ஋ʹͳΔ NT
24. MB[Z • "OESPJEͰ͸ΫϥεͷΠϯελϯεੜ੒࣌ʹ͸
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25. MB[Z • +BWB෩ͳΞϓϩʔν private var param: String? = null
26. MB[Z • +BWB෩ͳΞϓϩʔν private var param: String? = null override fun onCreate(savedInstanceState: Bundle?) { param = intent.getStringExtra("param") Log.d(TAG, param) }
27. MB[Z • +BWB෩ͳΞϓϩʔν private var param: String? = null override fun onCreate(savedInstanceState: Bundle?) { param = intent.getStringExtra("param") ?: throw IllegalArgumentException() Log.d(TAG, param) }
28. MB[Z • +BWB෩ͳΞϓϩʔν private var param: String? = null override fun onCreate(savedInstanceState: Bundle?) { param = intent.getStringExtra("param") ?: throw IllegalArgumentException() Log.d(TAG, param) }
29. MB[Z • +BWB෩ͳΞϓϩʔν private var param: String? = null override fun onCreate(savedInstanceState: Bundle?) { param = intent.getStringExtra("param") ?: throw IllegalArgumentException() Log.d(TAG, param) }
30. MB[Z • +BWB෩ͳΞϓϩʔν private var param: String? = null override fun onCreate(savedInstanceState: Bundle?) { param = intent.getStringExtra("param") ?: throw IllegalArgumentException() Log.d(TAG, param!!) } OVMMBCMFͳͷͰOPOOVMM΁ͷ
    ม׵͕ඞཁʹͳΔ
31. MB[Z • MBUFJOJUΛ࢖ͬͨํ๏ private lateinit var param: String override fun onCreate(savedInstanceState: Bundle?) { param = intent.getStringExtra("param") ?: throw IllegalArgumentException() Log.d(TAG, param) }
32. MB[Z • MBUFJOJUΛ࢖ͬͨํ๏ private lateinit var param: String override fun onCreate(savedInstanceState: Bundle?) { param = intent.getStringExtra("param") ?: throw IllegalArgumentException() Log.d(TAG, param) }
33. MB[Z • MBUFJOJUΛ࢖ͬͨํ๏ private lateinit var param: String override fun onCreate(savedInstanceState: Bundle?) { param = intent.getStringExtra("param") ?: throw IllegalArgumentException() Log.d(TAG, param) } private fun someOperation() { param = "overwritten with wrong value" } NVUBCMFͳͷͰ༧ظ͠ͳ͍
    ஋ͷॻ͖׵͕͑ൃੜ͠͏Δ
34. MB[Z • MBUFJOJUΛ࢖ͬͨํ๏ private lateinit var param: String override fun onCreate(savedInstanceState: Bundle?) { param = intent.getStringExtra("param") ?: throw IllegalArgumentException() Log.d(TAG, param) } private fun someOperation() { if (!::param.isInitialized) { param = intent.getStringExtra("param") } textView.text = param } ෳ਺ͷՕॴ͔Βࢀর͞ΕΔ৔߹ɺ
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35. MB[Z • MB[ZͳΒJNNVUBCMFͳϓϩύςΟͰ஗ԆॳظԽͰ͖Δ private val param: String by lazy { intent.getStringExtra("param") ?: throw IllegalArgumentException() } override fun onCreate(savedInstanceState: Bundle?) { Log.d(TAG, param) }
36. %FMFHBUFTOPU/VMM
37. %FMFHBUFTOPU/VMM • MBUFJOJU
    private var param: String by Delegates.notNull() override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) param = intent.getStringExtra("param") ?: throw IllegalArgumentException() Log.d(TAG, param) }
38. %FMFHBUFTOPU/VMM • MBUFJOJU͸ϓϦϛςΟϒܕʹ͸࢖༻Ͱ͖ͳ͍
39. %FMFHBUFTOPU/VMM • MBUFJOJUͷར༻Ͱ͖ͳ͍ϓϦϛςΟϒܕʹ
    • MBUFJOJU͸୯ͳΔϑΟʔϧυ͕ͩEFMFHBUJPO͸ϓϩύςΟຖ ʹΦϒδΣΫτΛ࣋ͭ͜ͱʹͳΔͷͰద੾ʹ࢖͍෼͚Λ
    • ௚઀ϑΟʔϧυΛ࣋ͨͳ͍ͷͰ+BWBͱͷޓ׵ੑʹ஫ҙ
40. %FMFHBUFTOPU/VMM • +BWBͱͷޓ׵ੑʹ஫ҙ class Sample { var notNull by Delegates.notNull<String>() lateinit var lateinitVar: String }
41. %FMFHBUFTOPU/VMM • +BWBͱͷޓ׵ੑʹ஫ҙ public final class Sample { @NotNull private final ReadWriteProperty notNull$delegate; @NotNull public String lateinitVar; public final void setNotNull(@NotNull String var1) {} @NotNull public final String getNotNull() {} public final void setLateinitVar(@NotNull String var1) {} @NotNull public final String getLateinitVar() {} }
42. %FMFHBUFTOPU/VMM • +BWBͱͷޓ׵ੑʹ஫ҙ public final class Sample { @NotNull private final ReadWriteProperty notNull$delegate; @NotNull public String lateinitVar; public final void setNotNull(@NotNull String var1) {} @NotNull public final String getNotNull() {} public final void setLateinitVar(@NotNull String var1) {} @NotNull public final String getLateinitVar() {} } QVCMJD͔ͭະॳظԽͷ
    ϑΟʔϧυͱͯ࣋ͭ͠
43. %FMFHBUFTOPU/VMM • +BWBͱͷޓ׵ੑʹ஫ҙ public final class Sample { @NotNull private final ReadWriteProperty notNull$delegate; @NotNull public String lateinitVar; public final void setNotNull(@NotNull String var1) {} @NotNull public final String getNotNull() {} public final void setLateinitVar(@NotNull String var1) {} @NotNull public final String getLateinitVar() {} } QSJWBUF͔ͭGJOBMͰϓϩύςΟΛ
    ௚઀ϑΟʔϧυͱͯ࣋ͨ͠ͳ͍
44. %FMFHBUFTOPU/VMM • +BWBͱͷޓ׵ੑͰ஫ҙ͢Δ఺
    MBUFJOJUͱͷҧ͍
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    • ܕ͕ҕৡઌΦϒδΣΫτͷܕ
45. %FMFHBUFTOPU/VMM • +BWBͱͷޓ׵ੑͰ஫ҙ͢Δ఺
    MBUFJOJUͱͷҧ͍
    • ϑΟʔϧυ͕QSJWBUF
    
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    • ܕ͕ҕৡઌΦϒδΣΫτͷܕ
    • %BHHFSͷϑΟʔϧυ*OKFDUJPO͕Ͱ͖ͳ͍ʂ
46. %FMFHBUFTOPU/VMM class Sample { var notNull by Delegates.notNull<String>() lateinit var lateinitVar: String }
47. %FMFHBUFTOPU/VMM class Sample { @Inject var notNull by Delegates.notNull<String>() @Inject lateinit var lateinitVar: String }
48. %FMFHBUFTOPU/VMM public final class Sample { @NotNull @Inject private final ReadWriteProperty notNull$delegate; @NotNull @Inject public String lateinitVar; public final void setNotNull(@NotNull String var1) {} public final String getNotNull() {} public final void setLateinitVar(@NotNull String var1) {} public final String getLateinitVar() {} }
49. %FMFHBUFTOPU/VMM public final class Sample { @NotNull @Inject private final ReadWriteProperty notNull$delegate; @NotNull @Inject public String lateinitVar; public final void setNotNull(@NotNull String var1) {} public final String getNotNull() {} public final void setLateinitVar(@NotNull String var1) {} public final String getLateinitVar() {} }
50. %FMFHBUFTOPU/VMM public final class Sample { @NotNull @Inject private final ReadWriteProperty notNull$delegate; @NotNull @Inject public String lateinitVar; public final void setNotNull(@NotNull String var1) {} public final String getNotNull() {} public final void setLateinitVar(@NotNull String var1) {} public final String getLateinitVar() {} } ϑΟʔϧυ*OKFDUJPOͰ͖ͳ͍
51. %FMFHBUFTOPU/VMM • %BHHFS͸ηολʔ*OKFDUJPO΋αϙʔτ͍ͯ͠Δ
    • OPU/VMM ʹݶΒͣ%FMFHBUFE
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52. %FMFHBUFTOPU/VMM class Sample { @Inject var notNull by Delegates.notNull<String>() }
53. %FMFHBUFTOPU/VMM class Sample { @Inject var notNull by Delegates.notNull<String>() }
54. %FMFHBUFTOPU/VMM class Sample { @set:Inject var notNull by Delegates.notNull<String>() }
55. %FMFHBUFTOPU/VMM public final class Sample { @NotNull @Inject private final ReadWriteProperty notNull$delegate; public final void setNotNull(@NotNull String var1) {} public final String getNotNull() {} }
56. %FMFHBUFTOPU/VMM public final class Sample { @NotNull private final ReadWriteProperty notNull$delegate; @Inject public final void setNotNull(@NotNull String var1) {} public final String getNotNull() {} }
57. %FMFHBUFTPCTFSWBCMFWFUPBCMF
58. %FMFHBUFTPCTFSWBCMFWFUPBCMF • PCTFSWBCMF
    • มߋΛݕ஌ͯ͠ॲཧΛ࣮ߦͰ͖Δ
    • WFUPBCMF
    • มߋલʹมߋ಺༰Λड͚ೖΕΔ͔൑ఆͰ͖Δ
59. %FMFHBUFTPCTFSWBCMFWFUPBCMF var inputtedText: String by Delegates.observable("init") { property, old, new -> println("inputted $inputtedText") } var positiveNumber: Long by Delegates.vetoable(1L) { property, old, new -> new > 0L }
60. %FMFHBUFTPCTFSWBCMFWFUPBCMF var inputtedText: String by Delegates.observable("init") { property, old, new -> println("inputted $inputtedText") } var positiveNumber: Long by Delegates.vetoable(1L) { property, old, new -> new > 0L } ஋ͷ୅ೖޙʹϒϩοΫͷॲཧΛ࣮ߦ
61. %FMFHBUFTPCTFSWBCMFWFUPBCMF var inputtedText: String by Delegates.observable("init") { property, old, new -> println("inputted $inputtedText") } var positiveNumber: Long by Delegates.vetoable(1L) { property, old, new -> new > 0L } ஋ͷ୅ೖલʹϒϩοΫΛ࣮ߦ͠
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62. 4UPSJOH
    1SPQFSUJFT
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63. 4UPSJOH
    1SPQFSUJFT
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    .BQ • LFZ͕4USJOHͷ.BQ͔ΒϓϩύςΟ໊Ͱ
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64. 4UPSJOH
    1SPQFSUJFT
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    .BQ class User(map: Map<String, Any>) { val name: String by map val age: Int by map }
65. 4UPSJOH
    1SPQFSUJFT
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    .BQ class User(map: Map<String, Any>) { val name: String by map val age: Int by map } Ωʔ͕4USJOHͷ.BQΛ
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66. 4UPSJOH
    1SPQFSUJFT
    JO
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    .BQ class User(map: Map<String, Any>) { val name: String by map val age: Int by map } val user = User( mapOf( "name" to "chibatching", "age" to 34 ) ) Ωʔ͕ϓϩύςΟ໊ͱ
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67. 4UPSJOH
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    .BQ class User(map: Map<String, Any>) { val name: String by map val age: Int by map } val user = User( mapOf( "name" to "chibatching", "age" to 34 ) ) println("name: ${user.name}, age: ${user.age}") // name: chibatching, age: 34
68. 4UPSJOH
    1SPQFSUJFT
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    B
    .BQ class User(map: Map<String, Any>) { val name: String by map val age: Int by map } val user = User( mapOf( "name" to "chibatching", "age" to 34 ) )
69. 4UPSJOH
    1SPQFSUJFT
    JO
    B
    .BQ class User(map: MutableMap<String, Any>) { var name: String by map var age: Int by map } val user = User( mutableMapOf( "name" to "chibatching", "age" to 34 ) )
70. 4UPSJOH
    1SPQFSUJFT
    JO
    B
    .BQ class User(map: MutableMap<String, Any>) { var name: String by map var age: Int by map } val user = User( mutableMapOf( "user" to "chibatching", "age" to 34 ) ) user.name = "chibatching Jr" user.age = 4 // {name=chibatching Jr, age=4}
71. TUEMJCͷ%FMFHBUFE
    1SPQFSUJFT • MB[Z
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    • %FMFHBUFTPCTFSWBCMFWFUPBCMF
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72. %FMFHBUFE
    1SPQFSUJFTΛ
    ࡞ͬͯΈΔ
73. ͳʹΛ%FMFHBUFE
    1SPQFSUJFTʹ͢Δ͔ • ڞ௨Խ͍ͨ͠TFUHFUॲཧ
    • TUEMJCʹ༻ҙ͞Ε͍ͯΔΑ͏ͳ΋ͷ
    • ΦϒδΣΫτ͔Βͷ஋औΓग़͠΍อଘʹ
    ఆܕతͳखଓ͖͕ඞཁͳ΋ͷ
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74. %FMFHBUFE
    1SPQFSUJFTʹ͢Δ΂͖Ͱͳ͍΋ͷ • ࣌ؒͷ͔͔Δॲཧɺ*0ॲཧͳͲ࣮ߦεϨουΛ
    ҙࣝ͢Δඞཁ͕͋ΔΑ͏ͳ΋ͷ
    • ݟͨ໨͸ϓϩύςΟ΁ͷΞΫηε
    • ར༻ऀ͸ॏ͍ͨॲཧ͕ߦΘΕΔ͜ͱΛ૝૾͢Δͷ͕
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75. 4IBSFE1SFGFSFODFTͷಡΈॻ͖Λ
    ؆୯ʹ͢Δ1SFGFSFODF%FMFHBUF
76. Կ͕ඞཁʁ val pref = context.getSharedPreferences("user_settings", Context.MODE_PRIVATE)
77. Կ͕ඞཁʁ val pref = context.getSharedPreferences("user_settings", Context.MODE_PRIVATE)
78. Կ͕ඞཁʁ val pref = context.getSharedPreferences("user_settings", Context.MODE_PRIVATE)  $POUFYU
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
79. Կ͕ඞཁʁ val pref = context.getSharedPreferences("user_settings", Context.MODE_PRIVATE)  $POUFYU
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
80. Կ͕ඞཁʁ val pref = context.getSharedPreferences("user_settings", Context.MODE_PRIVATE)  $POUFYU
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
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81. Կ͕ඞཁʁ val pref = context.getSharedPreferences("user_settings", Context.MODE_PRIVATE)  $POUFYU
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
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82. Կ͕ඞཁʁ val pref = context.getSharedPreferences("user_settings", Context.MODE_PRIVATE) pref.edit().putString("name", "chibatching").apply()  $POUFYU
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    ϑΝΠϧ໊
83. Կ͕ඞཁʁ val pref = context.getSharedPreferences("user_settings", Context.MODE_PRIVATE) pref.edit().putString("name", "chibatching").apply()  $POUFYU
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
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84. Կ͕ඞཁʁ val pref = context.getSharedPreferences("user_settings", Context.MODE_PRIVATE) pref.edit().putString("name", "chibatching").apply()  $POUFYU
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    ϑΝΠϧ໊
    
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85. Կ͕ඞཁʁ val pref = context.getSharedPreferences("user_settings", Context.MODE_PRIVATE) pref.edit().putString("name", "chibatching").apply() pref.getString("name", "default")  $POUFYU
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    ϑΝΠϧ໊
    
    1SFGFSFODFͷΩʔ
    
86. Կ͕ඞཁʁ val pref = context.getSharedPreferences("user_settings", Context.MODE_PRIVATE) pref.edit().putString("name", "chibatching").apply() pref.getString("name", "default")  $POUFYU
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    ϑΝΠϧ໊
    
    1SFGFSFODFͷΩʔ
    
87. Կ͕ඞཁʁ val pref = context.getSharedPreferences("user_settings", Context.MODE_PRIVATE) pref.edit().putString("name", "chibatching").apply() pref.getString("name", "default")  $POUFYU
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    ϑΝΠϧ໊
    
    1SFGFSFODFͷΩʔ
    
    
    σϑΥϧτ஋
88. Կ͕ඞཁʁ val pref = context.getSharedPreferences("user_settings", Context.MODE_PRIVATE) pref.edit().putString("name", "chibatching").apply() pref.getString("name", "default")  $POUFYU
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    ϑΝΠϧ໊
    
    1SFGFSFODFͷΩʔ
    
    
    σϑΥϧτ஋
89. • $POUFYU
    • ϑΝΠϧ໊
    • 1SFGFSFODFΩʔ
    • σϑΥϧτ஋ Կ͕ඞཁʁ
90. %FMFHBUFE
    1SPQFSUJFTͷجຊ • ҕৡઌΦϒδΣΫτͷ࠷௿৚݅
    • HFU7BMVFΦϖϨʔλ͕࣮૷͞Ε͍ͯΔ͜ͱ
    • NVUBCMFͳϓϩύςΟͷ৔߹͸
    TFU7BMVFΦϖϨʔλ͕࣮૷͞Ε͍ͯΔ͜ͱ
91. %FMFHBUFE
    1SPQFSUJFTͷجຊ class PreferenceDelegate { operator fun getValue( thisRef: Any?, property: KProperty<*>): String { return "delegated value" } operator fun setValue( thisRef: Any?, property: KProperty<*>, value: String) { } }
92. %FMFHBUFE
    1SPQFSUJFTͷجຊ class PreferenceDelegate { operator fun getValue( thisRef: Any?, property: KProperty<*>): String { return "delegated value" } operator fun setValue( thisRef: Any?, property: KProperty<*>, value: String) { } } HFU7BMVFʹ͸
    HFUUFSͷॲཧΛ࣮૷͢Δ
93. %FMFHBUFE
    1SPQFSUJFTͷجຊ class PreferenceDelegate { operator fun getValue( thisRef: Any?, property: KProperty<*>): String { return "delegated value" } operator fun setValue( thisRef: Any?, property: KProperty<*>, value: String) { } } TFU7BMVFʹ͸
    TFUUFSͷॲཧΛ࣮૷͢Δ
94. %FMFHBUFE
    1SPQFSUJFTͷجຊ class PreferenceDelegate { operator fun getValue( thisRef: Any?, property: KProperty<*>): String { return "delegated value" } operator fun setValue( thisRef: Any?, property: KProperty<*>, value: String) { } }
95. %FMFHBUFE
    1SPQFSUJFTͷجຊ class PreferenceDelegate : ReadWriteProperty<Any?, String> { operator fun getValue( thisRef: Any?, property: KProperty<*>): String { return "delegated value" } operator fun setValue( thisRef: Any?, property: KProperty<*>, value: String) { } } NVUBCMF
    
    
    
    
    3FBE8SJUF1SPQFSUZ
    JNNVUBCMF
    3FBE0OMZ1SPQFSUZ
96. %FMFHBUFE
    1SPQFSUJFTͷجຊ class PreferenceDelegate : ReadWriteProperty<Any?, String> { override operator fun getValue( thisRef: Any?, property: KProperty<*>): String { return "delegated value" } override operator fun setValue( thisRef: Any?, property: KProperty<*>, value: String) { } }
97. %FMFHBUFE
    1SPQFSUJFTͷجຊ class PreferenceDelegate : ReadWriteProperty<Any?, String> { override operator fun getValue( thisRef: Any?, property: KProperty<*>): String { return "delegated value" } override operator fun setValue( thisRef: Any?, property: KProperty<*>, value: String) { } }
98. %FMFHBUFE
    1SPQFSUJFTͷجຊ • ҕৡઌΦϒδΣΫτͷ࠷௿৚݅
    • HFU7BMVFΦϖϨʔλ͕࣮૷͞Ε͍ͯΔ͜ͱ
    • NVUBCMFͳϓϩύςΟͷ৔߹͸
    TFU7BMVFΦϖϨʔλ͕࣮૷͞Ε͍ͯΔ͜ͱ
    • 3FBE8SJUF1SPQFSUZ
    3FBE0OMZ1SPQFSUZΠϯλʔϑΣʔε
    Λ࣮૷͢Δͱ*%&Ͱิ׬͕Ͱָ͖ͯ
99. • ͱΓ͋͑ͣඞཁͳ΋ͷΛશͯίϯετϥΫλʹ
    • $POUFYU
    • ϑΝΠϧ໊
    • 1SFGFSFODFΩʔ
    • σϑΥϧτ஋ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
100. class PreferenceDelegate( fileName: String, context: Context, private val key: String, private val default: String ) : ReadWriteProperty<Any?, String> { private val preference = context.getSharedPreferences(fileName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(key, default)!! } 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
101. class PreferenceDelegate( fileName: String, context: Context, private val key: String, private val default: String ) : ReadWriteProperty<Any?, String> { private val preference = context.getSharedPreferences(fileName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(key, default)!! } 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
102. class PreferenceDelegate( fileName: String, context: Context, private val key: String, private val default: String ) : ReadWriteProperty<Any?, String> { private val preference = context.getSharedPreferences(fileName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(key, default)!! } 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
103. • ར༻͢ΔଆΛݟͯΈΔ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
104. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class MainActivity : AppCompatActivity() { private var userName: String by PreferenceDelegate("user_settings", this, "user_name", "") override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) findViewById<TextView>(R.id.user_name).text = userName findViewById<Button>(R.id.save_button).setOnClickListener { userName = findViewById<EditText>(R.id.input).text.toString() } }
105. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class MainActivity : AppCompatActivity() { private var userName: String by PreferenceDelegate("user_settings", this, "user_name", "") override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) findViewById<TextView>(R.id.user_name).text = userName findViewById<Button>(R.id.save_button).setOnClickListener { userName = findViewById<EditText>(R.id.input).text.toString() } }
106. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class MainActivity : AppCompatActivity() { private var userName: String by PreferenceDelegate("user_settings", this, "user_name", "") override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) findViewById<TextView>(R.id.user_name).text = userName findViewById<Button>(R.id.save_button).setOnClickListener { userName = findViewById<EditText>(R.id.input).text.toString() } }
107. • ΋͏গָ͠ʹ͍ͨ͠ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ private var userName: String by PreferenceDelegate("user_settings", this, "user_name", "")
108. • ΋͏গָ͠ʹ͍ͨ͠
     • ϓϩύςΟ໊ΩʔʹͰ͖ΔͱָʹͳΓͦ͏ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ private var userName: String by PreferenceDelegate("user_settings", this, "user_name", "")
109. • 4IBSFE1SFGFSFODFTͷΩʔʹϓϩύςΟ໊Λ࢖͍͍ͨ
     • %FMFHBUFE
     1SPQFSUZ͔ΒϓϩύςΟͷ৘ใΛ஌Γ͍ͨ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
110. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val key: String, private val default: String ) : ReadWriteProperty<Any?, String> { private val preference = context.getSharedPreferences(fileName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(key, default)!! }
111. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val key: String, private val default: String ) : ReadWriteProperty<Any?, String> { private val preference = context.getSharedPreferences(fileName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(key, default)!! }
112. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val key: String, private val default: String ) : ReadWriteProperty<Any?, String> { private val preference = context.getSharedPreferences(fileName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(key, default)!! } Ҿ਺ͷ,1SPQFSUZ͸
     ҕৡݩϓϩύςΟ
113. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val key: String, private val default: String ) : ReadWriteProperty<Any?, String> { private val preference = context.getSharedPreferences(fileName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(key, default)!! }
114. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val key: String, private val default: String ) : ReadWriteProperty<Any?, String> { private val preference = context.getSharedPreferences(fileName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(property.name, default)!! }
115. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val key: String, private val default: String ) : ReadWriteProperty<Any?, String> { private val preference = context.getSharedPreferences(fileName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(property.name, default)!! }
116. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val default: String ) : ReadWriteProperty<Any?, String> { private val preference = context.getSharedPreferences(fileName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(property.name, default)!! }
117. • ϓϩύςΟͷ৘ใ͸,1SPQFSUZ͔ΒऔಘͰ͖Δ
     • ͞·͟·ͳ৘ใ͕औಘՄೳ
     • OBNF
     • PQFOGJOBM
     • FUD
     • OBNFҎ֎ͷ৘ใ͸LPUMJOSFGMFDUύοέʔδ͕ඞཁ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
118. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class MainActivity : AppCompatActivity() { private var userName: String by PreferenceDelegate("user_settings", this, "user_name", "") override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) findViewById<TextView>(R.id.user_name).text = userName findViewById<Button>(R.id.save_button).setOnClickListener { userName = findViewById<EditText>(R.id.input).text.toString() } }
119. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class MainActivity : AppCompatActivity() { private var userName: String by PreferenceDelegate("user_settings", this, "") override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) findViewById<TextView>(R.id.user_name).text = userName findViewById<Button>(R.id.save_button).setOnClickListener { userName = findViewById<EditText>(R.id.input).text.toString() } }
120. • ΞϓϦશମͰ࢖͑ΔΑ͏ผͷΫϥεʹ੾Γग़͍ͨ͠
     • ϓϩύςΟ໊΍ϑΝΠϧ໊Λ
     5ZQP͢Δͱਖ਼͘͠஋͕औಘอଘͰ͖ͳ͍
     1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ private var userName: String by PreferenceDelegate("user_settings", this, "")
121. • ผͷΫϥεʹ੾Γग़͢ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(context: Context) { private val fileName = "user_settings" var userName by PreferenceDelegate(fileName, context, "") }
122. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class MainActivity : AppCompatActivity() { private var userName: String by PreferenceDelegate("user_settings", this, "") override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) findViewById<TextView>(R.id.user_name).text = userName findViewById<Button>(R.id.save_button).setOnClickListener { userName = findViewById<EditText>(R.id.input).text.toString() } }
123. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class MainActivity : AppCompatActivity() { private val userSettings by lazy { UserSettings(this) } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) findViewById<TextView>(R.id.user_name).text = userName findViewById<Button>(R.id.save_button).setOnClickListener { userName = findViewById<EditText>(R.id.input).text.toString() } }
124. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class MainActivity : AppCompatActivity() { private val userSettings by lazy { UserSettings(this) } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) findViewById<TextView>(R.id.user_name).text = userName findViewById<Button>(R.id.save_button).setOnClickListener { userName = findViewById<EditText>(R.id.input).text.toString() } }
125. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class MainActivity : AppCompatActivity() { private val userSettings by lazy { UserSettings(this) } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) findViewById<TextView>(R.id.user_name).text = userSettings.userName findViewById<Button>(R.id.save_button).setOnClickListener { userSettings.userName = findViewById<EditText>(R.id.input).text.toString() } }
126. • ผͷΫϥεʹ੾Γग़͕ͨ͠ʜ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(context: Context) { private val fileName = "user_settings" var userName by PreferenceDelegate(fileName, context, "") }
127. • ϓϩύςΟ͕૿͑Δͱʜ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(context: Context) { private val fileName = "user_settings" var userName by PreferenceDelegate(fileName, context, "") var iconUrl by PreferenceDelegate(fileName, context, "") var coverPhoto by PreferenceDelegate(fileName, context, "") }
128. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(context: Context) { private val fileName = "user_settings" var userName by PreferenceDelegate(fileName, context, "") var iconUrl by PreferenceDelegate(fileName, context, "") var coverPhoto by PreferenceDelegate(fileName, context, "") }
129. • Ϋϥε໊Λͦͷ··ϑΝΠϧ໊ʹͯ͠΋Αͦ͞͏ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(context: Context) { private val fileName = "user_settings" var userName by PreferenceDelegate(fileName, context, "") var iconUrl by PreferenceDelegate(fileName, context, "") var coverPhoto by PreferenceDelegate(fileName, context, "") }
130. • ϑΝΠϧ໊ΛϓϩύςΟ͕એݴ͞Ε͍ͯΔΫϥε໊
     ͔Βઃఆ͍ͨ͠
     • %FMFHBUFE
     1SPQFSUZ͔ΒϓϩύςΟ͕
     એݴ͞Ε͍ͯΔΫϥεͷ͜ͱΛ஌Γ͍ͨ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
131. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val default: String ) : ReadWriteProperty<Any?, String> { private val preference = context.getSharedPreferences(fileName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(property.name, default)!! }
132. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val default: String ) : ReadWriteProperty<Any?, String> { private val preference = context.getSharedPreferences(fileName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(property.name, default)!! } ϓϩύςΟ͕એݴ͞Ε͍ͯΔ
     ΫϥεΠϯελϯε
133. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val default: String ) : ReadWriteProperty<Any?, String> { private val preference = context.getSharedPreferences(fileName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(property.name, default)!! }
134. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val default: String ) : ReadWriteProperty<Any?, String> { private fun getPreferenceForClass(thisRef: Any?) = context.getSharedPreferences( thisRef?.javaClass?.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(property.name, default)!! }
135. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val default: String ) : ReadWriteProperty<Any?, String> { private fun getPreferenceForClass(thisRef: Any?) = context.getSharedPreferences( thisRef?.javaClass?.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { return preference.getString(property.name, default)!! }
136. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val default: String ) : ReadWriteProperty<Any?, String> { private fun getPreferenceForClass(thisRef: Any?) = context.getSharedPreferences( thisRef?.javaClass?.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(property.name, default)!! }
137. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( fileName: String, context: Context, private val default: String ) : ReadWriteProperty<Any?, String> { private fun getPreferenceForClass(thisRef: Any?) = context.getSharedPreferences( thisRef?.javaClass?.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(property.name, default)!! }
138. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( context: Context, private val default: String ) : ReadWriteProperty<Any?, String> { private fun getPreferenceForClass(thisRef: Any?) = context.getSharedPreferences( thisRef?.javaClass?.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(property.name, default)!! }
139. • HFU7BMVFTFU7BMVFͷύϥϝʔλ
     UIJT3FG
     ͸
     ϓϩύςΟΛએݴ͍ͯ͠ΔΫϥεΠϯελϯε
     1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
140. • ϑΝΠϧ໊ΛলུͰ͖ΔΑ͏ʹͳͬͨ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(context: Context) { private val fileName = "user_settings" var userName by PreferenceDelegate(fileName, context, "") var iconUrl by PreferenceDelegate(fileName, context, "") var coverPhoto by PreferenceDelegate(fileName, context, "") }
141. • ϑΝΠϧ໊ΛলུͰ͖ΔΑ͏ʹͳͬͨ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(context: Context) { var userName by PreferenceDelegate(context, "") var iconUrl by PreferenceDelegate(context, "") var coverPhoto by PreferenceDelegate(context, "") }
142. • $POUFYU΋লུͰ͖Δͱخ͍͠ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(context: Context) { var userName by PreferenceDelegate(context, "") var iconUrl by PreferenceDelegate(context, "") var coverPhoto by PreferenceDelegate(context, "") }
143. • HFU7BMVFTFU7BMVFͷύϥϝʔλ
     UIJT3FG
     ͸
     ϓϩύςΟΛએݴ͍ͯ͠ΔΫϥεΠϯελϯε
     1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
144. • HFU7BMVFTFU7BMVFͷύϥϝʔλ
     UIJT3FG
     ͸
     ϓϩύςΟΛએݴ͍ͯ͠ΔΫϥεΠϯελϯε
     • UIJT3FG͕DPOUFYUΛอ͍࣋ͯ͠Ε͹UIJT3FG͔Β
     औಘͰ͖ΔͷͰ͸ʁ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
145. • HFU7BMVFTFU7BMVFͷύϥϝʔλ
     UIJT3FG
     ͸
     ϓϩύςΟΛએݴ͍ͯ͠ΔΫϥεΠϯελϯε
     • UIJT3FG͕DPOUFYUΛอ͍࣋ͯ͠Ε͹UIJT3FG͔Β
     औಘͰ͖ΔͷͰ͸ʁ
     • ܕʮ"OZ ʯ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
146. • HFU7BMVFTFU7BMVFͷύϥϝʔλ
     UIJT3FG
     ͸
     ϓϩύςΟΛએݴ͍ͯ͠ΔΫϥεΠϯελϯε
     • UIJT3FG͕DPOUFYUΛอ͍࣋ͯ͠Ε͹UIJT3FG͔Β
     औಘͰ͖ΔͷͰ͸ʁ
     • ܕʮ"OZ ʯ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
147. • UIJT3FGͷܕ͸੍ݶ͢Δ͜ͱ͕Մೳ
     • ಛఆͷΫϥε಺ͰͷΈར༻Ͱ͖Δ%FMFHBUF͕࣮૷Ͱ͖Δ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
148. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(context: Context) { var userName by PreferenceDelegate(context, "") var iconUrl by PreferenceDelegate(context, "") var coverPhoto by PreferenceDelegate(context, "") }
149. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(context: Context) { var userName by PreferenceDelegate(context, "") var iconUrl by PreferenceDelegate(context, "") var coverPhoto by PreferenceDelegate(context, "") } interface PreferenceModel { val context: Context }
150. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(override val context: Context) : PreferenceModel { var userName by PreferenceDelegate(context, "") var iconUrl by PreferenceDelegate(context, "") var coverPhoto by PreferenceDelegate(context, "") } interface PreferenceModel { val context: Context }
151. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( context: Context, private val default: String ) : ReadWriteProperty<Any?, String> { private fun getPreferenceForClass(thisRef: Any?) = context.getSharedPreferences( thisRef?.javaClass?.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(property.name, default)!! }
152. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( context: Context, private val default: String ) : ReadWriteProperty<Any?, String> { private fun getPreferenceForClass(thisRef: Any?) = context.getSharedPreferences( thisRef?.javaClass?.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: Any?, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(property.name, default)!! }
153. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( context: Context, private val default: String ) : ReadWriteProperty<PreferenceModel, String> { private fun getPreferenceForClass(thisRef: Any?) = context.getSharedPreferences( thisRef?.javaClass?.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: PreferenceModel, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(property.name, default)!! } ܕΛࢦఆ͢Δ͜ͱͰ
     ಛఆͷΫϥε಺ͰͷΈ࢖͑ΔΑ͏
     ੍ݶ͢Δ͜ͱ͕Ͱ͖Δ
154. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( context: Context, private val default: String ) : ReadWriteProperty<PreferenceModel, String> { private fun getPreferenceForClass(thisRef: Any?) = context.getSharedPreferences( thisRef?.javaClass?.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: PreferenceModel, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(property.name, default)!! }
155. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( context: Context, private val default: String ) : ReadWriteProperty<PreferenceModel, String> { private fun getPreferenceForClass(thisRef: Any?) = context.getSharedPreferences( thisRef?.javaClass?.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: PreferenceModel, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(property.name, default)!! }
156. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( context: Context, private val default: String ) : ReadWriteProperty<PreferenceModel, String> { private fun getPreferenceForClass(thisRef: PreferenceModel) = thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: PreferenceModel, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(property.name, default)!! }
157. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( context: Context, private val default: String ) : ReadWriteProperty<PreferenceModel, String> { private fun getPreferenceForClass(thisRef: PreferenceModel) = thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: PreferenceModel, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(property.name, default)!! }
158. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( private val default: String ) : ReadWriteProperty<PreferenceModel, String> { private fun getPreferenceForClass(thisRef: PreferenceModel) = thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: PreferenceModel, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(property.name, default)!! }
159. • ϓϩύςΟͷఆ͕͖ٛͬ͢Γͱ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(override val context: Context) : PreferenceModel { var userName by PreferenceDelegate("") var iconUrl by PreferenceDelegate("") var coverPhoto by PreferenceDelegate("") }
160. • ར༻ଆ͸͖ͬ͢ΓͱͰ͖͕ͨ%FMFHBUFଆͰ͸ʜ
     • ౎౓4IBSFE1SFGFSFODFTΛऔಘ͍ͯ͠Δͷ͕ؾʹͳΔ
     • ϑΝΠϧ໊΍Ωʔ͸มΘΒͳ͍ͷͰຊ౰͸
     ίϯετϥΫλͰઃఆ͍ͨ͠ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
161. • QSPWJEF%FMFHBUFΦϖϨʔλΛ࢖͏͜ͱͰ
     %FMFHBUFE
     QSPQFSUZJFTͷόΠϯυ࣌ʹॲཧΛߦ͑Δ
     • 4JODF
     ,PUMJO
      1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
162. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( private val default: String ) : ReadWriteProperty<PreferenceModel, String> { private fun getPreferenceForClass(thisRef: PreferenceModel) = thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: PreferenceModel, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(property.name, default)!! }
163. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( private val default: String ) : ReadWriteProperty<PreferenceModel, String> { private fun getPreferenceForClass(thisRef: PreferenceModel) = thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: PreferenceModel, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(property.name, default)!! }
164. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( private val key: String, private val default: String ) : ReadWriteProperty<PreferenceModel, String> { private fun getPreferenceForClass(thisRef: PreferenceModel) = thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: PreferenceModel, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(key, default)!! }
165. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( private val preference: SharedPreferences, private val key: String, private val default: String ) : ReadWriteProperty<PreferenceModel, String> { private fun getPreferenceForClass(thisRef: PreferenceModel) = thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: PreferenceModel, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(key, default)!! }
166. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( private val preference: SharedPreferences, private val key: String, private val default: String ) : ReadWriteProperty<PreferenceModel, String> { private fun getPreferenceForClass(thisRef: PreferenceModel) = thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE) override operator fun getValue( thisRef: PreferenceModel, property: KProperty<*> ): String { val preference = getPreferenceForClass(thisRef) return preference.getString(key, default)!! }
167. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceDelegate( private val preference: SharedPreferences, private val key: String, private val default: String ) : ReadWriteProperty<PreferenceModel, String> { override operator fun getValue( thisRef: PreferenceModel, property: KProperty<*> ): String { return preference.getString(key, default)!! }
168. • QSPWJEF%FMFHBUFͰҕৡઌΫϥεΛఏڙ͢ΔΫϥεΛ࣮૷ 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ
169. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceLoader(private val default: String) { operator fun provideDelegate( thisRef: PreferenceModel, property: KProperty<*> ): ReadWriteProperty<PreferenceModel, String> { return PreferenceDelegate( thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE ), property.name, default ) } }
170. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceLoader(private val default: String) { operator fun provideDelegate( thisRef: PreferenceModel, property: KProperty<*> ): ReadWriteProperty<PreferenceModel, String> { return PreferenceDelegate( thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE ), property.name, default ) } }
171. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceLoader(private val default: String) { operator fun provideDelegate( thisRef: PreferenceModel, property: KProperty<*> ): ReadWriteProperty<PreferenceModel, String> { return PreferenceDelegate( thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE ), property.name, default ) } }
172. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceLoader(private val default: String) { operator fun provideDelegate( thisRef: PreferenceModel, property: KProperty<*> ): ReadWriteProperty<PreferenceModel, String> { return PreferenceDelegate( thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE ), property.name, default ) } }
173. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceLoader(private val default: String) { operator fun provideDelegate( thisRef: PreferenceModel, property: KProperty<*> ): ReadWriteProperty<PreferenceModel, String> { return PreferenceDelegate( thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE ), property.name, default ) } }
174. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceLoader(private val default: String) { operator fun provideDelegate( thisRef: PreferenceModel, property: KProperty<*> ): ReadWriteProperty<PreferenceModel, String> { return PreferenceDelegate( thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE ), property.name, default ) } }
175. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceLoader(private val default: String) { operator fun provideDelegate( thisRef: PreferenceModel, property: KProperty<*> ): ReadWriteProperty<PreferenceModel, String> { return PreferenceDelegate( thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE ), property.name, default ) } }
176. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceLoader(private val default: String) { operator fun provideDelegate( thisRef: PreferenceModel, property: KProperty<*> ): ReadWriteProperty<PreferenceModel, String> { return PreferenceDelegate( thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE ), property.name, default ) } }
177. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class PreferenceLoader(private val default: String) { operator fun provideDelegate( thisRef: PreferenceModel, property: KProperty<*> ): ReadWriteProperty<PreferenceModel, String> { return PreferenceDelegate( thisRef.context.getSharedPreferences( thisRef.javaClass.simpleName, Context.MODE_PRIVATE ), property.name, default ) } }
178. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(override val context: Context) : PreferenceModel { var userName by PreferenceDelegate("") var iconUrl by PreferenceDelegate("") var coverPhoto by PreferenceDelegate("") }
179. 1SFGFSFODF%FMFHBUFΛ࣮૷͢Δ class UserSettings(override val context: Context) : PreferenceModel { var userName by PreferenceLoader("") var iconUrl by PreferenceLoader("") var coverPhoto by PreferenceLoader("") }
180. • ·ͱΊ
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     • UIJT3FGύϥϝʔλ͸ϓϩύςΟ͕એݴ͞Ε͍ͯΔΫϥεͷ
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     • όΠϯυ࣌ʹॲཧ΍ϓϩύςΟͷݕࠪ౳Λ
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181. -FUT
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182. 5JQT
183. %FMFHBUFE
     1SPQFSUJFTͷ
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184. • %FMFHBUFE
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     QSPQFSUJFTͷJOMJOF࠷దԽ
185. %FMFHBUFE
     QSPQFSUJFTͷJOMJOF࠷దԽ class DelegateSample { var myProp: String by MyDelegate() }
186. %FMFHBUFE
     QSPQFSUJFTͷJOMJOF࠷దԽ class DelegateSample { private val myProp$delegate = MyDelegate() var myProp: String get() = myProp$delegate.getValue(this, this::myProp) set(value: String) = myProp$delegate.setValue(this, this::myProp, value) }
187. %FMFHBUFE
     QSPQFSUJFTͷJOMJOF࠷దԽ public final class DelegateSample { static final KProperty[] $$delegatedProperties = new KProperty[]{(KProperty)Reflection.mutableProperty1( new MutablePropertyReference1Impl( Reflection.getOrCreateKotlinClass(DelegateSample.class), "myProp", "getMyProp()Ljava/lang/String;"))}; @NotNull private final MyDelegate myProp$delegate = new MyDelegate(); @NotNull public final String getMyProp() { return this.myProp$delegate.getValue(this, $$delegatedProperties[0]); } public final void setMyProp(@NotNull String var1) { Intrinsics.checkParameterIsNotNull(var1, "<set-?>"); this.myProp$delegate.setValue(this, $$delegatedProperties[0], var1); } }
188. %FMFHBUFE
     QSPQFSUJFTͷJOMJOF࠷దԽ public final class DelegateSample { static final KProperty[] $$delegatedProperties = new KProperty[]{(KProperty)Reflection.mutableProperty1( new MutablePropertyReference1Impl( Reflection.getOrCreateKotlinClass(DelegateSample.class), "myProp", "getMyProp()Ljava/lang/String;"))}; @NotNull private final MyDelegate myProp$delegate = new MyDelegate(); @NotNull public final String getMyProp() { return this.myProp$delegate.getValue(this, $$delegatedProperties[0]); } public final void setMyProp(@NotNull String var1) { Intrinsics.checkParameterIsNotNull(var1, "<set-?>"); this.myProp$delegate.setValue(this, $$delegatedProperties[0], var1); } }
189. %FMFHBUFE
     QSPQFSUJFTͷJOMJOF࠷దԽ public final class DelegateSample { static final KProperty[] $$delegatedProperties = new KProperty[]{(KProperty)Reflection.mutableProperty1( new MutablePropertyReference1Impl( Reflection.getOrCreateKotlinClass(DelegateSample.class), "myProp", "getMyProp()Ljava/lang/String;"))}; @NotNull private final MyDelegate myProp$delegate = new MyDelegate(); @NotNull public final String getMyProp() { return this.myProp$delegate.getValue(this, $$delegatedProperties[0]); } public final void setMyProp(@NotNull String var1) { Intrinsics.checkParameterIsNotNull(var1, "<set-?>"); this.myProp$delegate.setValue(this, $$delegatedProperties[0], var1); } }
190. • %FMFHBUFE
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     ௨ৗͷϓϩύςΟΑΓ΋Φʔόʔϔου͕େ͖͍
     • QSPWJEF%FMFHBUFHFU7BMVFTFU7BMVFʹ౉͢
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191. • 'SPN
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192. • ͜ͷػೳͷίϛοτϩάΛݟΔͱʜ %FMFHBUFE
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193. • ,1SPQFSUZOBNF͚ͩ͸ಛผʹࢀরՄೳͳΑ͏ʹ͢Δ
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     • ࠓͷॴ࣮૷͸͞Ε͍ͯͳͦ͞͏ %FMFHBUFE
     QSPQFSUJFTͷJOMJOF࠷దԽ
194. طଘΫϥε΁ͷ%FMFHBUJPO
195. • طଘΫϥεʹ%FMFHBUJPO͍ͨ͠
     
     • طଘΫϥεͷ֦ுͱ͍͑͹֦ுؔ਺ طଘΫϥεʹ%FMFHBUJPO͢Δ
196. طଘΫϥεʹ%FMFHBUJPO͢Δ operator fun String.getValue(thisRef: Any?, property: KProperty<*>) = this.length
197. طଘΫϥεʹ%FMFHBUJPO͢Δ operator fun String.getValue(thisRef: Any?, property: KProperty<*>) = this.length class ExtensionDelegate { val length: Int by "delegate" fun main() { println(length) // 8 } }
198. طଘΫϥεʹ%FMFHBUJPO͢Δ operator fun <T> SharedPreferences.getValue( thisRef: Any?, property: KProperty<*> ): T = this.all[property.name] as? T ?: throw IllegalArgumentException() operator fun <T> SharedPreferences.setValue( thisRef: Any?, property: KProperty<*>, value: T ) { val editor = edit() when (value) { is String -> editor.putString(property.name, value) is Boolean -> editor.putBoolean(property.name, value) // 省略 } editor.apply() }
199. • ֦ுؔ਺ʹΑΔҕৡ
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