Travelling Across Asia - Our Journey from Java to Kotlin

Given at Android Makers FR - Paris, 2018

Transcript

1. TRAVELLING ACROSS ASIA OUR JOURNEY FROM JAVA TO KOTLIN Amal Kakaiya @K4KYA @DeliverooEng
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
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
15. # TravellingAcrossAsia @K4KYA
16. # TravellingAcrossAsia @K4KYA
17. FIND YOUR OWN PACE # TravellingAcrossAsia @K4KYA
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
78. THANK YOU WE’RE HIRING Amal Kakaiya @K4KYA