Kotlin頻出表現

Kotlinでよくつかう文/式等

TwitterID変えました。@lvla0805 -> @MoyuruAizawa

Transcript

1. ,PUMJO
   සग़දݱ !MWMB
2. lvla lvla0805 Ѫᖒ
   ๖
   .PZVSV
   "J[BXB
    -FBE
   FOHJOFFS
   PG
   QBJST
   %JW
   FVSFLB
   *OD
    FVSFLB
   ,PUMJO
   &WBOHFMJTU
    +BWB,PUMJO3Y+BWB
4.  QBJST
    $PVQMFT
    NBUDI
   HSPVQ
   *"$
    OPX
   IJSJOH
6. NFFUT
7. WBM
8. ‣ SFBEPOMZ
   ‣ جຊWBMΛར༻͍ͯ͠Δɻ
   ‣ ňͦΕWBSͰ͋Δඞཁ͋Δͷ ʼn
   ‣ ΈΜͳ+BWBॻ࣌͘ʹpOBMΛ͚ͭΔΑ͏ʹͳͬͨ WBM val readOnliy = 10 readOnliy = 20 // error
9. /VMMBCMF
10. ‣ /VMMΛڐ༰͢Δܕͱɺ/VMMΛڋ൱͢Δܕ͕໌֬ʹΘ͚ΒΕ͍ͯΔ
    ‣ OPU/VMMʹ͸OVMM͸୅ೖͰ͖ͳ͍͠ɺOVMMBCMFΛ୅ೖ͢Δ͜ͱ΋ग़དྷͳ ͍
    ‣ ৗʹ/VMMΛҙࣝͯ͠ίʔσΟϯά͢Δ͜ͱʹͳΔ
    /VMMBCMF val nullable: String? = null var notNull: String = null // error notNull: String = nullable // error
11. 4BGF
    $BMM
12. ‣ /VMMBCMF͕/VMMͷ৔߹ɺOVMM͕ฦ٫͞ΕΔɻ
    ‣ /VMMBCMF͕/VMMͰͳ͍৔߹ɺؔ਺͕࣮ߦ͞ΕΔϓϩύςΟͷ஋͕ฦ٫ ͞ΕΔɻ 4BGF
    $BMM nullablePerson?.toString() nullablePerson?.age
13. %FMFHBUFE
    1SPQFSUJFT
14. ‣ ϓϩύςΟͷॳظԽΛҕৡͰ͖Δ
    ‣ ॳظԽΛ஗ԆͰ͖Δ
    ‣ ϥΠϑαΠΫϧʹґଘ͢Δ΋ͷͰ΋WBMͰॳظԽͰ͖Δ %FMFHBUFE
    1SPQFSUJFT val view by bindView(R.id.view) val string by lazy { getString(R.string.foo) }
15. &YUFOTJPO
    'VODUJPO
16. ‣ ܧঝ͢Δࣄͳ͘ɺطଘΫϥεʹؔ਺Λ௥ՃͰ͖Δɻ &YUFOTJPO
    'VODUJPO fun Activity.toWeb(uri: Uri) { startActivity( Intent(Intent.ACTION_VIEW, uri) ) } fun Subscription.addTo(subscriptions: CompositeSubscription) { subscriptions(this) }
17. 4JOHMF
    &YQSFTTJPO
    'VODUJPO
18. ‣ ؔ਺ͷ࣮૷͕୯Ұࣜͷ৔߹ɺฦΓ஋ͷએݴɺϒϩοΫɺSFUVSOΛলུ Ͱ͖Δɻ 4JOHMF
    &YQSFTTJPO
    'VODUJPO @Provide fun provideApplicationContext() = applicationContext
19. )JHIFS0SEFS
    'VODUJPO
20. ‣ ؔ਺ΛҾ਺ʹͱͬͨΓ
    ‣ ؔ਺Λฦ٫͢Δؔ਺
    ‣ +BWB͸ؔ਺͕ϑΝʔετΫϥεΦϒδΣΫτ͡Όͳ͍͔Β͜Ε͕Ͱ͖ ͳ͍ )JHIFS0SEFS
    'VODUJPO fun foo( function: (Int)->Unit ) { … } fun bar(): (Int)->String { … }
21. ‣ 7JFXΛҾ਺ʹͱΓ6OJU 㲈7PJE Λฦ٫͢Δؔ਺ͱಉ౳Ͱ͸ 4". public interface OnClickListener { void onClick(View var1); }
22. ‣ ؔ਺ͭͷΠϯλʔϑΣʔεΛҾ਺ʹऔΔؔ਺ʹ͸ɺؔ਺Λ౉ͤ·͢
    ‣ هड़ྔΊͬͪΌݮΔʜ 4". view.setOnClickListener({ view -> view.visibility = View.GONE }) view.setOnClickListener { view -> view.visibility = View.GONE } view.setOnClickListener { it.visibility = View.GONE }
23. MFU
24. ‣ ؔ਺Λ౉͢ͱɺͦͷؔ਺Λ࣮ߦͯ͘͠ΕΔɻ
    ‣ 4BGF
    $BMMͰMFUΛ࣮ߦ͍ͯ͠ΔͷͰɺOVMMͰͳ͍৔߹ʹͷΈ࣮ߦ͞Ε Δɻ
    MFU nullable?.let { it.doSomething }
25. BQQMZ
26. ‣ Ϩγʔό 'PP'SBHNFOU ͷϓϩύςΟ΍ؔ਺Λར༻͢Δؔ਺Λ౉͢
    ‣ ͦΕΒ͕ద༻͞ΕͨϨγʔό͕ฦ٫͞ΕΔɻ BQQMZ FooFragment().apply { arguments = Bundle().apply { pustString("key", "value") } }
27. ‣ 4JOHMF
    &YQSFTTJPO
    'VODUJPOͱ૊Έ߹ΘͤΔͱ͖ͬ͢Γ BQQMZ fun newInstance() = FooFragment().apply { arguments = Bundle().apply { pustString("key", "value") } }
28. EFDMBSJOH
    QSPQFSUJFT
    BOE
    JOJUJBMJ[JOH
    UIFN
    GSPN
    QSJNBSZ
    DPOTUSVDUPS
29. ‣ ϓϩύςΟͷએݴͱॳظԽΛɺϓϥΠϚϦίϯετϥΫλͰߦ͑Δ
    ‣ ϗϯτָʜ EFDMBSJOH
    QSPQFSUJFT
    BOE
    JOJUJBMJ[JOH
    UIFN
    GSPN
    QSJNBSZ
    DPOTUSVDUPS class Person(val firstName: String, val lastName: String, var age: Int) { // ... }
30. %BUB
    $MBTT
31. ‣ FRVBMT
    IBTI$PEF
    UP4USJOH
    DPQZ ΛίϯύΠϧ࣌ʹੜ੒ͯ͠ ͘ΕΔ
    ‣ Ξοϓσʔτ͞Εͳ͍FRVBMT ͱ͞Α͏ͳΒͰ͖Δɻ
    %BUB
    $MBTT data class Person(val firstName: String, val lastName: String, var age: Int)
32. OUBSPLOJU
33. ‣ ֦ுؔ਺Λ࢖ͬͯBTTFSU5IBUΛ͍͍ײ͡ʹͯ͘͠ΕΔ
    ‣ ΋͏͜Ε͕ͳ͍ͱςετ͸ॻ͚ͳ͍ʜ LOJU @Test fun test() { (1 + 2).should be 3 // assertThat(1 + 2, `is`(3)) }
34. TZTZBHJLNPDLJUP
35. ‣ ֦ுؔ਺Λ࢖ͬͯNPDLJUPΛ͍͍ײ͡ʹͯ͘͠ΕΔɻ
    ‣ ͜Ε΋ͳ͍ͱςετͰ͖ͳ͍ʜ LNPDLJUP var item: Item = mock() item.length().invoked.thenReturn(10) item.length().should be 10 item.verify().length()
36. 5IBOL
    ZPV