"Bring your Kotlin to Work" Day

Transcript

1. "Bring Your Kotlin To Work" Day September 2017 Maybe
2. Guillermo Orellana Senior Keyboard Smasher github.com/wiyarmir https://www.linkedin.com/in/guillermoorellana @wiyarmir
4. – bringyourdogtoworkday.co.uk “[…] the presence of pets can substantially reduce a person’s stress level in the workplace. Increased job satisfaction, team co-operation and morale have all been reported in employees that spend the workday with their pets”
5. – me “[…] the presence of Kotlin can substantially reduce a person’s stress level in the workplace. Increased job satisfaction, team co-operation and morale have all been reported in employees that spend the workday with Kotlin”
10. The case for Kotlin
11. Don’t stay in your Java bubble
13. Learn the basics
14. val var
15. Type Type?
16. @NonNull private final String name = "Java"; private val name: String = "Kotlin"
17. It's OK to write Java-ish Kotlin
18. Improve by doing
20. Let the IDE help you
24. Let other people help you
26. Let the Kotlin community help you
28. Kotlin won't make bad code good
29. The case against Kotlin
31. Fighting the compiler
32. @JvmField @JvmStatic @JvmName @JvmSuppressWildcards @JvmWildcard @JvmOverloads
35. Final by default
41. Style guide
43. ¯\_(ツ)_/¯
44. Quizz time!
45. class MarketDataViewModel { init { compositeDisposable.add(bindToMarketData()) } val compositeDisposable = CompositeDisposable() fun bindToMarketData(): Disposable = TODO() }
47. class MarketDataViewModel { val compositeDisposable = CompositeDisposable() init { compositeDisposable.add(bindToMarketData()) } fun bindToMarketData(): Disposable = TODO() }
48. class MarketDataViewModel { val compositeDisposable = CompositeDisposable() init { compositeDisposable.add(bindToMarketData()) } val mapper = TODO() fun bindToMarketData(): Disposable = retrieveMarketData.getStream() .map(mapper) .subscribe() }
49. RuntimeException
50. class MarketDataViewModel { val compositeDisposable = CompositeDisposable() init { compositeDisposable.add(bindToMarketData()) } val mapper = TODO() fun bindToMarketData(): Disposable = retrieveMarketData.getStream() .map(mapper) .subscribe() }
51. class MarketDataViewModel { val compositeDisposable = CompositeDisposable() init { compositeDisposable.add(bindToMarketData()) } val mapper = TODO() fun bindToMarketData(): Disposable = retrieveMarketData.getStream() .map(mapper) .subscribe() }
52. class MarketDataViewModel { val compositeDisposable = CompositeDisposable() init { compositeDisposable.add(bindToMarketData()) } val mapper = TODO() fun bindToMarketData(): Disposable = retrieveMarketData.getStream() .map(mapper) .subscribe() }
53. class MarketDataViewModel { val compositeDisposable = CompositeDisposable() init { compositeDisposable.add(bindToMarketData()) } val mapper = TODO() fun bindToMarketData(): Disposable = retrieveMarketData.getStream() .map(mapper) .subscribe() }
54. class MarketDataViewModel { val compositeDisposable = CompositeDisposable() init { compositeDisposable.add(bindToMarketData()) } val mapper = TODO() fun bindToMarketData(): Disposable = retrieveMarketData.getStream() .map(mapper) .subscribe() }
55. RuntimeException
56. class MarketDataViewModel { val compositeDisposable = CompositeDisposable() val mapper = TODO() init { compositeDisposable.add(bindToMarketData()) } fun bindToMarketData(): Disposable = retrieveMarketData.getStream() .map(mapper) .subscribe() }
57. What I like from Kotlin
58. Data Classes
59. "POJOs"
60. public class Balance { @NonNull private final BalanceType type; private final int value; public Balance(@NonNull BalanceType type, int value) { this.type = type; this.value = value; } @NonNull public BalanceType getType() { return type; } public int getValue() { return value;
61. return type == balance.type; } @Override public int hashCode() { int result = type.hashCode(); result = 31 * result + value; return result; } @Override public String toString() { return "Balance{" + "type=" + type + ", value=" + value + '}'; } }
62. data class Balance (val type: BalanceType, val value: Int)
63. data class Balance ( val type: BalanceType = Invalid, val value: Int = 0 )
64. Named parameters
65. fun fromEntity(e: ModerationEntity) = ModerationModel( header = e.header, body = e.message, ctaPrimary = e.ctaPrimary, ctaSecondary = e.ctaSecondary, photos = e.photos )
66. Sealed classes
67. sealed class BalanceResult { data class Balance( val type: BalanceKind = Invalid, val value: Int = 0 ): BalanceResult() object BalanceError: BalanceResult() }
68. Bonus points
69. class MarketDataRepository( private val store: ReactiveStore<String, MarketData>, private val marketDataService: MarketDataService, private val marketDataMapper: MarketDataMapper) { fun getAllMarketData(): Flowable<Optional<List<MarketData >>> = store.getAll() fun fetchMarketData(): Completable = marketDataService.getMarketPrice() .subscribeOn(Schedulers.io()) .observeOn(Schedulers.computation()) .map(marketDataMapper) .doOnSuccess({ store.replaceAll(it) }) .toCompletable() } }
70. Looks great in slides
71. Fits great in slides
72. Kotlin is here to stay
73. Kotlin is here to stay
74. Thank you!
75. Inspiration • The Case Against Kotlin - Pinterest Engineering • Kotlin for grumpy Java developers - Pinterest Engineering • Kotlin: The Good, The Bad, and The Ugly
76. Links • Try Kotlin - https://try.kotlinlang.org/ • Kotlin Koans - https://try.kotlinlang.org/#/Kotlin%20Koans/ • Kategory - https://github.com/kategory/kategory/ • Kotlinlang Slack - slack.kotlinlang.org
77. Image credits • Android Studio Logo - Android Open Source Project (CCBY) • Renibeni - C. Mclean (Free Domain) • John Charles Dollman - Table d'Hote at a Dogs' Home (Free Domain) • Forbidden - Wikimedia (Free Domain) • 869018 - Pixbay (Free Domain)
78. Questions? github.com/badoo https://habrahabr.ru/company/badoo/ @BadooDev