Travelling Across Asia - Our Journey from Java to Kotlin

Transcript

1. TRAVELLING ACROSS ASIA OUR JOURNEY FROM JAVA TO KOTLIN Amal

   Kakaiya @K4KYA @DeliverooEng
2. None

3. DISCLAIMER: COULD TAKE MORE THAN 20 HOURS

4. Java Kotlin AutoValue/Lombok Data classes Streams support Standard lib functions

   Retrolambda Built in lambda support Butterknife Kotterknife/delegate properties # TravellingAcrossAsia @K4KYA

5. ADOPTING A NEW LANGUAGE IS A HUGE STEP # TravellingAcrossAsia

   @K4KYA

6. TESTS ARE AN EASY WAY TO GET STARTED # TravellingAcrossAsia

   @K4KYA

7. TESTS ARE AN EASY WAY TO GET STARTED BUT NOT

   VERY EXCITING # TravellingAcrossAsia @K4KYA

8. HOW MUCH COULD WE IMPROVE THE MAIN APP? # TravellingAcrossAsia

   @K4KYA
9. None

10. DON’T GO ROGUE! # TravellingAcrossAsia @K4KYA

11. KOTLIN HOUR THE MEETING YOU ACTUALLY WANT TO GO TO

    # TravellingAcrossAsia @K4KYA

12. YOU CAN’T START USING A LANGUAGE WITHOUT EVERYBODY KNOWING IT

    # TravellingAcrossAsia @K4KYA

13. DO WE REALLY WANT TO ADD ANOTHER DEPENDENCY? # TravellingAcrossAsia

    @K4KYA
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15. # TravellingAcrossAsia @K4KYA

16. # TravellingAcrossAsia @K4KYA

17. FIND YOUR OWN PACE # TravellingAcrossAsia @K4KYA

18. None

19. CONVERT ALL THE THINGS!! # TravellingAcrossAsia @K4KYA

20. IT WASN’T A SMOOTH RIDE # TravellingAcrossAsia @K4KYA

21. LEARN FROM EACH OTHER # TravellingAcrossAsia @K4KYA

22. WE REVIEW CODE EVERY DAY # TravellingAcrossAsia @K4KYA

23. # TravellingAcrossAsia @K4KYA

24. ANDROID STUDIO IS YOUR FRIEND # TravellingAcrossAsia @K4KYA

25. private fun mapToIds(items: List<Item>): List<String> { val ids = mutableListOf<String>()

    for (item in items) { ids.add(item.id) } return ids } # TravellingAcrossAsia @K4KYA

26. private fun mapToIds(items: List<Item>): List<String> { val ids = items.map

    { it.id } return ids } # TravellingAcrossAsia @K4KYA

27. private fun mapToIds(items: List<Item>): List<String> { return items.map { it.id

    } } # TravellingAcrossAsia @K4KYA

28. private fun mapToIds(items: List<Item>): List<String> = items.map { it.id }

    # TravellingAcrossAsia @K4KYA

29. WHAT’S THIS CODE DOING? # TravellingAcrossAsia @K4KYA

30. private final mapToId(Ljava/util/List;)Ljava/ util/List; L0 LINENUMBER 2 L0 ALOAD 1

    CHECKCAST java/lang/Iterable ASTORE 2 ———————— 75 more lines ———————— # TravellingAcrossAsia @K4KYA

31. private final List mapToId(List items) { Iterable $receiver$iv = (Iterable)items;

    Collection destination$iv$iv = (Collection)(new ArrayList(CollectionsKt.collectionSizeOrDefault($receiver$ iv, 10))); Iterator var5 = $receiver$iv.iterator(); while(var5.hasNext()) { Object item$iv$iv = var5.next(); Item it = (Item)item$iv$iv; String var12 = it.id; destination$iv$iv.add(var12); } return (List)destination$iv$iv; } # TravellingAcrossAsia @K4KYA

32. EXPECT THE UNEXPECTED # TravellingAcrossAsia @K4KYA

33. val extraOptions = items .map { "Item $it" } .takeIf

    { showExtraOptions } # TravellingAcrossAsia @K4KYA

34. Iterable $receiver$iv = (Iterable)items; Collection $receiver$iv = (Collection)(new ArrayList(CollectionsKt.collectionSizeOrDefault($receiver$iv, 10)));

    Iterator var8 = $receiver$iv.iterator(); while(var8.hasNext()) { Object item$iv$iv = var8.next(); String it = (String)item$iv$iv; String var17 = "Item " + it; $receiver$iv.add(var17); } List var10000 = (List)$receiver$iv; List extraOptions = showExtraOptions ? var10000 : null; # TravellingAcrossAsia @K4KYA

35. Iterable $receiver$iv = (Iterable)items; Collection $receiver$iv = (Collection)(new ArrayList(CollectionsKt.collectionSizeOrDefault($receiver$iv, 10)));

    Iterator var8 = $receiver$iv.iterator(); while(var8.hasNext()) { Object item$iv$iv = var8.next(); String it = (String)item$iv$iv; String var17 = "Item " + it; $receiver$iv.add(var17); } List var10000 = (List)$receiver$iv; List extraOptions = showExtraOptions ? var10000 : null; # TravellingAcrossAsia @K4KYA

36. val extraOptions = if (showExtraOptions) items .map { "Item $it"

    } else null # TravellingAcrossAsia @K4KYA

37. CONVERTING CODE # TravellingAcrossAsia @K4KYA

38. CONVERTING CODE # TravellingAcrossAsia @K4KYA

39. CONVERTING CODE # TravellingAcrossAsia @K4KYA

40. CONVERTING CODE ⌘⌥⇧K Ctrl+Alt+⇧+K # TravellingAcrossAsia @K4KYA

41. CONVERTING CODE # TravellingAcrossAsia @K4KYA

42. CONVERTING CODE # TravellingAcrossAsia @K4KYA

43. CONVERTING CODE # TravellingAcrossAsia @K4KYA

44. CONVERSION CREEP # TravellingAcrossAsia @K4KYA

45. NULLPOINTEREXCEPTION # TravellingAcrossAsia @K4KYA

46. NULLPOINTEREXCEPTION # TravellingAcrossAsia @K4KYA

47. KOTLINNULLPOINTEREXCEPTION # TravellingAcrossAsia @K4KYA

48. CONSIDER NULLABILITY WHEN IMPLEMENTING A JAVA INTERFACE private val passwordActionListener

    = TextView.OnEditorActionListener { _: TextView, _: Int, _: KeyEvent -> login(password()) } # TravellingAcrossAsia @K4KYA

49. CONSIDER NULLABILITY WHEN IMPLEMENTING A JAVA INTERFACE private val passwordActionListener

    = TextView.OnEditorActionListener { _: TextView, _: Int, _: KeyEvent -> login(password()) } # TravellingAcrossAsia @K4KYA

50. CONSIDER NULLABILITY WHEN IMPLEMENTING A JAVA INTERFACE private val passwordActionListener

    = TextView.OnEditorActionListener { _: TextView, _: Int, _: KeyEvent -> login(password()) } # TravellingAcrossAsia @K4KYA

51. CONSIDER NULLABILITY WHEN IMPLEMENTING A JAVA INTERFACE private val passwordActionListener

    = TextView.OnEditorActionListener { _: TextView, _: Int, _: KeyEvent -> login(password()) } # TravellingAcrossAsia @K4KYA

52. CONSIDER NULLABILITY WHEN IMPLEMENTING A JAVA INTERFACE private val passwordActionListener

    = TextView.OnEditorActionListener { _: TextView, _: Int, _: KeyEvent? -> login(password()) } # TravellingAcrossAsia @K4KYA

53. CONSIDER NULLABILITY WHEN IMPLEMENTING A JAVA INTERFACE private val passwordActionListener

    = TextView.OnEditorActionListener { _: TextView, _: Int, _: KeyEvent? -> login(password()) } # TravellingAcrossAsia @K4KYA

54. CONVERTING CODE class VerifyActivity: BaseActivity<VerifyPresenter>, VerifyScreen { override val message:

    String = getString(R.string.verify_error) # TravellingAcrossAsia @K4KYA

55. CONVERTING CODE class VerifyActivity: BaseActivity<VerifyPresenter>, VerifyScreen { override val message:

    String get() = getString(R.string.verify_error) # TravellingAcrossAsia @K4KYA

56. USE VERSION CONTROL EFFECTIVELY # TravellingAcrossAsia @K4KYA

57. USE VERSION CONTROL EFFECTIVELY AND YOUR TEAM WILL ❤ YOU

    # TravellingAcrossAsia @K4KYA

58. VERSION HISTORY # TravellingAcrossAsia @K4KYA

59. VERSION CONTROL CONVERSION AS ONE COMMIT # TravellingAcrossAsia @K4KYA

60. VERSION CONTROL MERGE CONVERSIONS QUICKLY # TravellingAcrossAsia @K4KYA

61. VERSION CONTROL # TravellingAcrossAsia @K4KYA

62. VERSION CONTROL SHARE WHAT YOU LEARNED # TravellingAcrossAsia @K4KYA

63. SHARE WHAT YOU LEARNED VERSION CONTROL # TravellingAcrossAsia @K4KYA

64. SHARE WHAT YOU LEARNED VERSION CONTROL # TravellingAcrossAsia @K4KYA

65. VERSION CONTROL LEAVE IN RETURN TYPES WHEN IT MAKES SENSE

    # TravellingAcrossAsia @K4KYA

66. VERSION CONTROL private fun showPrompt(confirmed: Boolean) = zip(flipper().confirmDrinkingAgeEnabled(), just(confirmed) {

    enabled, confirmed -> enabled && (!confirmed) } # TravellingAcrossAsia @K4KYA

67. VERSION CONTROL private fun showPrompt(confirmed: Boolean): Observable<Boolean> = zip(flipper().confirmDrinkingAgeEnabled(), just(confirmed)

    { enabled, confirmed -> enabled && (!confirmed) } # TravellingAcrossAsia @K4KYA

68. # TravellingAcrossAsia @K4KYA

69. ANDROIDANNOTATIONS AUTOVALUE BUTTERKNIFE LOMBOK DAGGER CUSTOM ANNOTATION PROCESSOR # TravellingAcrossAsia

    @K4KYA

70. KAPT KAY - AY - PEE - TEE # TravellingAcrossAsia

    @K4KYA

71. KAPT VS LOMBOK A TRUE STORY # TravellingAcrossAsia @K4KYA

72. KAPT VS LOMBOK A TRUE STORY # TravellingAcrossAsia @K4KYA

73. WHAT WOULD WE CHANGE? # TravellingAcrossAsia @K4KYA

74. CONVERT UTIL CLASSES EARLY # TravellingAcrossAsia @K4KYA

75. @file:JvmName(“ViewUtils") @JvmName("showView") fun View.show(visible: Boolean) { visibility = if (visible)

    VISIBLE else GONE } # TravellingAcrossAsia @K4KYA

76. DO WHAT WORKS FOR YOUR TEAM # TravellingAcrossAsia @K4KYA

77. None

78. THANK YOU WE’RE HIRING Amal Kakaiya @K4KYA