Kotlin頻出表現

Transcript

1. 1.

   ,PUMJO
   සग़දݱ !MWMB

2. 2.

   lvla lvla0805 Ѫᖒ
   ๖
   .PZVSV
   "J[BXB
    -FBE
   FOHJOFFS
   PG
   QBJST
   %JW
   FVSFLB
   *OD
    FVSFLB
   ,PUMJO
   &WBOHFMJTU
   

    +BWB,PUMJO3Y+BWB
3. 3.

   None
4. 4.

    QBJST
    $PVQMFT
    NBUDI
   HSPVQ
   *"$
    OPX
   IJSJOH

5. 5.

   None
6. 6.

   NFFUT

7. 7.

   WBM

8. 8.

   ‣ SFBEPOMZ
   ‣ جຊWBMΛར༻͍ͯ͠Δɻ
   ‣ ňͦΕWBSͰ͋Δඞཁ͋Δͷ ʼn
   ‣ ΈΜͳ+BWBॻ࣌͘ʹpOBMΛ͚ͭΔΑ͏ʹͳͬͨ WBM

   val readOnliy = 10 readOnliy = 20 // error
9. 9.

   /VMMBCMF

10. 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. 11.

    4BGF
    $BMM

12. 12.

    ‣ /VMMBCMF͕/VMMͷ৔߹ɺOVMM͕ฦ٫͞ΕΔɻ
    ‣ /VMMBCMF͕/VMMͰͳ͍৔߹ɺؔ਺͕࣮ߦ͞ΕΔϓϩύςΟͷ஋͕ฦ٫ ͞ΕΔɻ 4BGF
    $BMM nullablePerson?.toString() nullablePerson?.age

13. 13.

    %FMFHBUFE
    1SPQFSUJFT

14. 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. 15.

    &YUFOTJPO
    'VODUJPO

16. 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. 17.

    4JOHMF
    &YQSFTTJPO
    'VODUJPO

18. 18.

    ‣ ؔ਺ͷ࣮૷͕୯Ұࣜͷ৔߹ɺฦΓ஋ͷએݴɺϒϩοΫɺSFUVSOΛলུ Ͱ͖Δɻ 4JOHMF
    &YQSFTTJPO
    'VODUJPO @Provide fun provideApplicationContext() = applicationContext

19. 19.

    )JHIFS0SEFS
    'VODUJPO

20. 20.

    ‣ ؔ਺ΛҾ਺ʹͱͬͨΓ
    ‣ ؔ਺Λฦ٫͢Δؔ਺
    ‣ +BWB͸ؔ਺͕ϑΝʔετΫϥεΦϒδΣΫτ͡Όͳ͍͔Β͜Ε͕Ͱ͖ ͳ͍ )JHIFS0SEFS
    'VODUJPO fun foo(

    function: (Int)->Unit ) { … } fun bar(): (Int)->String { … }
21. 21.

    ‣ 7JFXΛҾ਺ʹͱΓ6OJU 㲈7PJE Λฦ٫͢Δؔ਺ͱಉ౳Ͱ͸ 4". public interface OnClickListener { void

    onClick(View var1); }
22. 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. 23.

    MFU

24. 24.

    ‣ ؔ਺Λ౉͢ͱɺͦͷؔ਺Λ࣮ߦͯ͘͠ΕΔɻ
    ‣ 4BGF
    $BMMͰMFUΛ࣮ߦ͍ͯ͠ΔͷͰɺOVMMͰͳ͍৔߹ʹͷΈ࣮ߦ͞Ε Δɻ
    MFU nullable?.let { it.doSomething }

25. 25.

    BQQMZ

26. 26.

    ‣ Ϩγʔό 'PP'SBHNFOU ͷϓϩύςΟ΍ؔ਺Λར༻͢Δؔ਺Λ౉͢
    ‣ ͦΕΒ͕ద༻͞ΕͨϨγʔό͕ฦ٫͞ΕΔɻ BQQMZ FooFragment().apply { arguments

    = Bundle().apply { pustString("key", "value") } }
27. 27.

    ‣ 4JOHMF
    &YQSFTTJPO
    'VODUJPOͱ૊Έ߹ΘͤΔͱ͖ͬ͢Γ BQQMZ fun newInstance() = FooFragment().apply { arguments =

    Bundle().apply { pustString("key", "value") } }
28. 28.

    EFDMBSJOH
    QSPQFSUJFT
    BOE
    JOJUJBMJ[JOH
    UIFN
    GSPN
    QSJNBSZ
    DPOTUSVDUPS

29. 29.

    ‣ ϓϩύςΟͷએݴͱॳظԽΛɺϓϥΠϚϦίϯετϥΫλͰߦ͑Δ
    ‣ ϗϯτָʜ EFDMBSJOH
    QSPQFSUJFT
    BOE
    JOJUJBMJ[JOH
    UIFN
    GSPN
    QSJNBSZ
    DPOTUSVDUPS class Person(val firstName: String, val

    lastName: String, var age: Int) { // ... }
30. 30.

    %BUB
    $MBTT

31. 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. 32.

    OUBSPLOJU

33. 33.

    ‣ ֦ுؔ਺Λ࢖ͬͯBTTFSU5IBUΛ͍͍ײ͡ʹͯ͘͠ΕΔ
    ‣ ΋͏͜Ε͕ͳ͍ͱςετ͸ॻ͚ͳ͍ʜ LOJU @Test fun test() { (1

    + 2).should be 3 // assertThat(1 + 2, `is`(3)) }
34. 34.

    TZTZBHJLNPDLJUP

35. 35.

    ‣ ֦ுؔ਺Λ࢖ͬͯNPDLJUPΛ͍͍ײ͡ʹͯ͘͠ΕΔɻ
    ‣ ͜Ε΋ͳ͍ͱςετͰ͖ͳ͍ʜ LNPDLJUP var item: Item = mock()

    item.length().invoked.thenReturn(10) item.length().should be 10 item.verify().length()
36. 36.

    5IBOL
    ZPV