Kotlin 더 잘 활용하기

GDG Korea Android

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1. ؊ ա਷ Kotlin ഝਊߨ਷? I love kotlin Taehwan
2. ࣗѐ • GDG Seoul ਍৔૓ • RGP Korea ਃӝਃ উ٘۽੉٘ ѐߊ • Է ݆਷ ѐߊ੗о غ੗ ࠶۽Ӓ ਍ ৔ - http://thdev.tech • Udemy ௏ౣܽ ъ੄
3. Kotlin ؊ ੜ ࢎਊೞ۰ݶ?
4. Kotlin ೟ण ߑߨ જ਷ ଼җ ݆਷ ޙࢲ ࠁӝ ӝࠄ ௏٘ ٮۄ ೞҊ, Convert ೧ࠁӝ թٜ੉ જ׮ח ۄ੉࠳۞ܻ ഝਊ ௏٘ ઴੉ӝ(let, apply, with, run, also ١)
5. ೞ૑݅ Kotlin݅ ೟णೞӝূ ই૒ Javaܳ ݽܳ ࣽ হ׮ ۞׬ ழ࠳о ծ૑݅ ੉೧ೡࣻ۾ য۵׮ Kotlinਸ ખ ؊ ੜ ঌ۰ݶ Effective Java ੉೧
6. Ӓېب ੉Ѥ ੉೧ೞݶ જ׮ Lambdas Kotlin Extension Higher-Order function ੉ 3 о૑ ੉೧ೞݶ Kotlin ഝਊࢿ੉ ֫ইઉਃ
7. Kotlin Extension Kotlinਸ ೟णೞח ׼न਷ ੉޷ ঌҊ ੓׮. let, run, apply, with, also and more.
8. Kotlin Extension public inline fun <T> T.apply(block: T.() -> Unit): T { contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) } block() return this } // use val button = Button(this).apply { text = "Button" textSize = resources.getDimension(R.id.button_text_size) }
9. Kotlin Extension public inline fun <T> T.apply(block: T.() -> Unit): T { contract { callsInPlace(block, InvocationKind.EXACTLY_ONCE) } block() return this } // use val button = Button(this).apply { text = "Button" textSize = resources.getDimension(R.id.button_text_size) } Extension Higher-Order function Lambdas
10. ੉޷ ੜ ഝਊ ઺੉׮. let, apply, run ١ ݅ ੜ ঌইب Kotlin য۵૑ ঋ׮ Ө਷ ղਊ਷ ա઺ী ଺ইоݶࢲ ੊൦׮.
11. Kotlin Extension ૒੽ ٜ݅যࠁ੗ 1 ױ҅ - String੉ Emptyо ইפݶ callback ߉ӝ interface Callback { fun notEmptyString(param: String) } fun notEmptyString(param: String?, callback: Callback) { if (!param.isNullOrEmpty()) { callback.notEmptyString(param!!) } }
12. Kotlin Extension ٜ݅যࠁ੗ 1 ױ҅ - String੉ Emptyо ইפݶ callback ߉ӝ पઁ ࢎਊ਷ notEmptyString(null, object : Callback { override fun notEmptyString(param: String) { // Use NotNull param } })
13. Kotlin Extension੉ۆ? Java୊ۢ UtilClassܳ ૒੽ ૑੿ೞ૑ ঋҊ, ё୓੄ ഛ੢ਸ ઁҕ StringUtil.notEmptyString() -> text.notEmptyString() functionҗ ೐۽ಌ౭(val/var) ݽف ഛ੢ਸ ઁҕ Generic ੸ਊ оמ
14. Kotlin Extension ٜ݅যࠁ੗
15. Kotlin Extension ٜ݅যࠁ੗ 2 ױ҅ - Extension ੸ਊ Receiver type fun String?.notEmptyString(callback: Callback) fun notEmptyString(param: String?, callback: Callback) fun notEmptyString( String? . callback: Callback)
16. Kotlin Extension ٜ݅যࠁ੗ 2 ױ҅ - Extension ੸ਊ fun String?.notEmptyString(callback: Callback) { if (!this.isNullOrEmpty()) { callback.notEmptyString(this!!) } } Receiver object Receiver type
17. Kotlin Extension ٜ݅যࠁ੗ 2 ױ҅ - Extension ੸ਊ notEmptyString(null, object : Callback { override fun notEmptyString(param: String) { // Use Message } }) null , notEmptyString( .
18. Kotlin Extension ٜ݅যࠁ੗ 2 ױ҅ - Extension ੸ਊ val name: String? = "Taehwan" name.notEmptyString(object : Callback { override fun notEmptyString(param: String) { // Use Message } })
19. 3 ױ҅ Kotlin Extension ੸ਊ೮૑݅ ӭՔೞ૑ ঋ׮. Listener??? Listener ؀न Higher-Order Functionਸ ࢎਊ೧ࠁ੗
20. Higher-Order function੉ۆ? functionਸ parameter۽ ੹׳ೞѢա, return ೡ ࣻ ੓׮ functionਸ ೐۽ಌ౭ب(val/var) о૕ ࣻ ੓׮
21. Higher-Order function ୡӝച val higherOrder: () -> Boolean = { false } fun higherOrder(block: () -> String) { block() }
22. Higher-Order function ୡӝച val higherOrder: () -> Boolean = { false } Method return type Function initialization return value
23. Higher-Order function ୡӝച val higherOrder: (param: String) -> Boolean = { false } Method Parameters param -> Kotlin lambdasח 1ѐ੄ parameters ࢤۚ оמ > ؀न it ఃਕ٘ ࢎਊ
24. ୶о۽ Higher-Order function Kotlin Extension ੸ਊب оמ
25. Higher-Order function ੸ਊೞӝ ੹ী val higherOrder: String?.() -> Boolean = { false } Method Receiver type val name: String? = "Taehwan" name.higherOrder()
26. Higher-Order function ੸ਊೞӝ 3 ױ҅ - Higher-Order function ੸ਊ fun String?.notEmptyString(callback: (String) -> Unit) { if (!this.isNullOrEmpty()) { callback(this!!) } } fun String?.notEmptyString(callback: Callback) { if (!this.isNullOrEmpty()) { callback.notEmptyString(this!!) } }
27. Higher-Order function ੸ਊೞӝ 3 ױ҅ - Higher-Order function ੸ਊ val name: String? = "Taehwan" name.notEmptyString({ println("notEmptyString $it") }) ( ) function ݃૑݄ Higher-Order functionীࢲ ࣗҚഐ()ח ࢤۚೡ ࣻ ੓׮.
28. Higher-Order function ੸ਊೞӝ fun String?.notEmptyString( callback: (String) -> Unit, callback2: () -> Unit) { if (!this.isNullOrEmpty()) { callback(this!!) } } "Taehwan".notEmptyString({ println("notEmptyString $it") }, { // something } , )
29. 3ѐח ঌও׮ Lambdas Kotlin Extension Higher-Order function Kotlin ؀ࠗ࠙੄ ۄ੉࠳۞ܻ णٙ оמ
30. Kotlin extension ખ ؊ ࠁ੗ public final void notEmptyString(@Nullable String $receiver, @NotNull Function1 callback) { Intrinsics.checkParameterIsNotNull(callback, "callback"); CharSequence var3 = (CharSequence)$receiver; if (var3 != null && var3.length() != 0) { if ($receiver == null) { Intrinsics.throwNpe(); } callback.invoke($receiver); } } public final void notEmptyTest() { this.notEmptyString("Taehwan", (Function1)null.INSTANCE); }
31. Kotlin extension ખ ؊ ࠁ੗ public final void notEmptyString(@Nullable String $receiver, @NotNull Function1 callback) { Intrinsics.checkParameterIsNotNull(callback, "callback"); CharSequence var3 = (CharSequence)$receiver; if (var3 != null && var3.length() != 0) { if ($receiver == null) { Intrinsics.throwNpe(); } callback.invoke($receiver); } } public final void notEmptyTest() { this.notEmptyString("Taehwan", (Function1)null.INSTANCE); } ೣࣻ ഐ୹੉ ੌযաঠ ೡө?
32. inline ഝਊ inlineਸ ୶о inlineਸ ୶оೣਵ۽ॄ kotlin extension ௏٘ܳ inline ೧ળ׮ Ѿҗ੸ਵ۽ function ഐ୹ ௏٘о ࢎۄ૓׮
33. inline ഝਊ if (!this.isNullOrEmpty()) { callback(this!!) } } fun String?.notEmptyString(callback: (String) -> Unit) {
34. inline ഝਊ - ࢎਊೞח ௏٘ীࢲ this.notEmptyString("Taehwan", (Function1)null.INSTANCE); -> public final void notEmptyTest() { String $receiver$iv = "Taehwan"; CharSequence var3 = (CharSequence)$receiver$iv; if (var3.length() != 0) { String var5 = "notEmptyString " + $receiver$iv; System.out.println(var5); } }
35. Kotlin DSLs (Domain-specific language)
36. DSLs (Domain-specific language) SQLীࢲ ൔೞѱ ࠅ ࣻ ੓׮. Select … / Delete … ѾҴ খীࢲ ੉ঠӝೠ 3о૑ܳ ੜ ഝਊೞݶ DSLਸ औѱ ੸ਊೡ ࣻ ੓׮.
37. inline fun Int.plus(param: Int) = this + param DSLs (Domain-specific language) 1 plus 10 . (10)
38. inline if (!this.isNullOrEmpty()) { callback(this!!) } } fun String?.notEmptyString(callback: String.() -> Unit) { DSLs (Domain-specific language) “Taehwan" notEmptyString { println("notEmptyString $this") } .
39. String.() -> Unit DSLs (Domain-specific language) Parameters Receiver type Return type
40. KTX Android KTX
41. Kotlin Android KTX Jetpack family Android - Kotlin ࢎਊ ಞ੄ܳ ذח extensions AndroidX ಁః૑۽ ઁҕ
 implementation ‘androidx.core:core-ktx:1.0.0-alpha1’ Android : https://developer.android.com/kotlin/ktx API : https://github.com/android/android-ktx API reference documentation : https://android.github.io/android-ktx/core-ktx/ Android Jetpack: sweetening Kotlin development with Android KTX (Google I/O '18)
42. /** * Creates and shows a [Toast] with the given [text] * * @param duration Toast duration, defaults to [Toast.LENGTH_SHORT] */ inline fun Context.toast(text: CharSequence, duration: Int = Toast.LENGTH_SHORT): Toast { return Toast.makeText(this, text, duration).apply { show() } } Use -> toast(“Message”) Kotlin Android KTX
43. inline fun Context.toast(text: CharSequence, duration: Int = Toast.LENGTH_SHORT): Toast { return Toast.makeText(this, text, duration).apply { show() } } infix ୶оೞݶ? messageо ઺੼ੋ ҃਋ ੉৬ э੉ ೡ ࣻ ੓׮ ೞ૑݅ durationب ೙ਃೞ׮ݶ? inline fun Context.toast(message: () -> String) { toast(message()) } toast { "Message" }
44. data class ToastData(val message: String, val duration: Int) class ToastDataBuilder { var message: String = "" var duration: Int = Toast.LENGTH_SHORT fun build(): ToastData = ToastData(message, duration) } message/duration ݽف ࢸ੿ೞ੗
45. inline fun Context.toast(message: () -> String) { toast(message()) } message/duration ݽف ࢸ੿ೞ੗ inline fun Context.toast(body: ToastDataBuilder.() -> Unit) { val builder = ToastDataBuilder() builder.body() val item = builder.build() toast(item.message, item.duration) }
46. toast { "Message" } message/duration ݽف ࢸ੿ೞ੗ toast { message = "Message" } toast { message = "Message" duration = Toast.LENGTH_SHORT }
47. inline fun Context.toast(body: () -> Pair<String, Int>) { val (message, duration) = body() toast(message, duration) } toast { “Message" to Toast.LENGTH_SHORT } Pair ੉ਊ೧ࢲ ୊ܻ?
48. ݃ஜ I Love Kotlin
49. private val yourViewModel: YourViewModel by lazyInject // create Your ViewModel YourViewModel(..., ..., ...) } ੉۠Ѫب ٜ݅ ࣻ ੓׮. ੉Ѧ ೞӝਤೠ ௏٘ח ড 30઴ ॳחҔীࢶ ױ 3઴ https://thdev.tech/LifecycleExtensions/
50. ѾҴ Lambdas Kotlin Extension Higher-Order function 3ѐ݅ ঌݶ KTXܳ ށۋযب ؊ औѱ ѐߊೡ ࣻ ੓׮.
51. хࢎ೤פ׮ taehwan@thdev.net GDG Seoul ਍৔૓ Taehwan ইې ੉ݫੌ۽...