新言語KotlinでAndroidプログラミング #DroidKaigi

Transcript

1. 1.

   ৽ݴޠ KotlinͰ Androidϓϩάϥϛϯά 
   %SPJE,BJHJ
   ! ೔ຊ,PUMJOϢʔβάϧʔϓ
 ௕ᖒ
   ଠ࿠
   !OHTX@UBSP ͜ͱΓΜ

2. 2.

   ࣗݾ঺հ

3. 3.

   ͸͡Ί·ͯ͠ʂ w ௕ᖒ
   ଠ࿠
   !OHTX@UBSP
   w ࢓ࣄͰ͸+BWB
   "OESPJEɺͱ͖Ͳ͖4DBMB
   w ࡀɺֈ࠲ɺͱ͕େ޷͖

4. 4.

   Θͨ͠ͱAndroid w ग़ձ͍͸೥ɻ)5"Ͱ༡ΜͰΈͨͷ͕࠷ॳ
   w ݸਓͰʮເͱຐ๏ͷ଴ͪ࣌ؒʯͱ͍͏ΞϓϦΛ։ ൃɾެ։͍ͯ͠·͢
   ສ%-
   w ॻ੶΍ٕज़ܥಉਓࢽͳͲʹܞΘΒ͍͍ͤͯͨͩͨ

   ܦݧ͕͋Γ·͢
5. 5.

   Θͨ͠ͱKotlin w ເதʹͳΓ࢝Ίͨͷ͸೥
   w Ҏདྷɺϒϩά΍ษڧձͰ৘ใൃ৴
   w 4PGUXBSF%FTJHO ٕධ Ͱ,PUMJOهࣄΛ࿈ࡌத

6. 6.

   ΋͘͡ 
   ,PUMJOͱ͸
   
   +BWBͱൺ΂Δ
   
   ,PUMJOͰ"OESPJEϓϩάϥϛϯά

7. 7.

   1. Kotlinͱ͸

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   ࣭໰ Kotlinͱ͍͏ϓϩάϥϛϯάݴޠ Λฉ͍ͨ͜ͱ͕͋Γ·͔͢ʁ

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   w !+BLF8IBSUPO͞Μ
   w ʮ6TJOH
   1SPKFDU
   ,PUMJO
   GPS
   "OESPJEʯ
   w !LJSJNJO͞Μ
   w ʮ೥ͷ"OESPJE։ൃ͸,PUMJOͰܾ·Γ͔΋ ͠Εͳ͍ʯ Androidք۾Ͱόζͬͨʁ

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    Kotlinͱ͸

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    Kotlinͱ͸ Better Java

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    w ೥Նʹ+FU#SBJOTʹΑΓൃද
    w Φʔϓϯιʔε
    "QBDIF
    -JDFOTF
    
    w +7.ݴޠɺBMU+4ɺ"OESPJE΋αϙʔτ
    w ੩తܕ෇͚ΦϒδΣΫτࢦ޲ݴޠ

    Kotlinͱ͸ (ৄ͘͠)
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    ଞͷJVMݴޠͱͷҧ͍͸

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    ଞͷJVMݴޠͱͷҧ͍͸ ϚΠϧυ ݱ࣮ݟͯΔײ

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    Kotlinͷಛ௃ ؆୯ ҆શ

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    2. Javaͱൺ΂Δ

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    Hello World (Java) class HelloWorld { public static void main(String[]

    args) { System.out.println("Hello, world!"); } }
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    Hello World (Kotlin) fun main(args: Array<String>) { println("Hello, world!") }

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    Hello World (Kotlin) fun main(args: Array<String>) { println("Hello, world!") }

    τοϓϨϕϧʹ
    ؔ਺Λஔ͚Δ ഑ྻʹ
    δΣωϦΫε ηϛίϩϯ
    ෆཁ
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    ม਺ (Java) final int a = 0;

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    ม਺ (Kotlin) val a = 0

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    ม਺ (Kotlin) val a = 0 ܕਪ࿦ Մมͳม਺ʹ͸
    WBSΩʔϫʔυΛ

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    Ϋϥε (Java) class User { private final long id; private

    final String name; public User(long id, String name) { this.id = id; this.name = Objects.requireNonNull(name); } public long getId() { return id; } public String getName() { return name; } / / toString, equals, hashCodeͱ͔ }
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    Ϋϥε (Kotlin) class User(val id: Long, val name: String) {

    / / toString, equals, hashCodeͱ͔ }
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    Ϋϥε (Kotlin) class User(val id: Long, val name: String) {

    / / toString, equals, hashCodeͱ͔ } ίϯετϥΫλҾ਺͕
    ͦͷ··ϓϩύςΟʹ
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    dataΞϊςʔγϣϯ data class User(val id: Long, val name: String)

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    σʔλΫϥε val taro = User(123, "Taro") println(taro.id) / / =>

    123 println(taro.name) / / => Taro println(taro) / / => User(id=123, name=Taro)
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    ؔ਺ܕΠϯλϑΣʔε (Java) / / anonymous class button.setOnClickListener(new View.OnClickListener() { @Override

    public void onClick(View v) { toast("Clicked!"); } }); ! / / lambda button.setOnClickListener(v -> toast("Clicked!"));
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    ؔ਺ܕΠϯλϑΣʔε (Kotlin) var count = 0 button.setOnClickListener { toast("${count++}") }

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    ؔ਺ܕΠϯλϑΣʔε (Kotlin) var count = 0 button.setOnClickListener { toast("${count++}") }

    Ϋϩʔδϟ
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    ߴ֊ؔ਺ͰίϨΫγϣϯૢ࡞ (1..999) .filter { it % 3 == 0 ||

    it % 5 == 0 } .reduce { a, b -> a + b }
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    ߴ֊ؔ਺ͰίϨΫγϣϯૢ࡞ (1..999) .filter { it % 3 == 0 ||

    it % 5 == 0 } .reduce { a, b -> a + b } ʮΠϯϥΠϯؔ਺ʯ
    ؔ਺Ϧςϥϧ͕ల։͞Ε
    ΦϒδΣΫτΛੜ੒͠ͳ͍
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    ಠࣗศརϝιου (Java) / / ఆٛ static void toast(Context c, String

    s) {...} ! / / ݺͼग़͠ MyUtils.toast(context, "Hello");
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    ಠࣗศརϝιου (Kotlin) / / ఆٛ fun Context.toast(s: String) {...} !

    / / ݺͼग़͠ context.toast("Hello") ! / / ݺͼग़͠(ActivityͳͲͷத) toast("Hello")
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    ಠࣗศརϝιου (Kotlin) / / ఆٛ fun Context.toast(s: String) {...} !

    / / ݺͼग़͠ context.toast("Hello") ! / / ݺͼग़͠(ActivityͳͲͷத) toast("Hello") ϝιουΛੜ΍ͤΔ
    ʮ֦ுؔ਺ʯ ੩తʹղܾ͞ΕΔʂ
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    Optional (Java) String a = "hoge"; Optional<String> b = Optional.of("fuga");

    Optional<String> c = null;
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    Optional (Java) String a = "hoge"; Optional<String> b = Optional.of("fuga");

    Optional<String> c = null; ΦϒδΣΫτੜ੒ ୭ʹ΋OVMM͸ࢭΊΒΕͳ͍ʂ
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    Optional (Kotlin) val a: String = "hoge" val b: String

    = null / / NG ! val c: String? = "hoge" val d: String? = null / / OK ! d.toUpperCase() / / NG
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    NULL҆શ val a: String? = "hoge" val b: String? =

    null ! if (a != null) a.toUpperCase() else null / / => HOGE if (b != null) b.toUpperCase() else null / / => null ! a?.toUpperCase() / / => HOGE b?.toUpperCase() / / => null
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    NULL҆શ val a: String? = "hoge" val b: String? =

    null ! if (a != null) a.toUpperCase() else null / / => HOGE if (b != null) b.toUpperCase() else null / / => null ! a?.toUpperCase() / / => HOGE b?.toUpperCase() / / => null OVMMͰͳ͍͜ͱ͕อূ͞Ε͍ͯΔ
    ৔ॴͰ͸/PU/VMMܕͱͯ͠ѻ͑Δ
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    3. KotlinͰ Androidϓϩάϥϛϯά

42. 42.

    Android StudioͰ࢖͏ 
    ී௨ʹϓϩδΣΫτΛ࡞੒
    
    +BWB
    
    ,PUMJO
    ม׵
    Φϓγϣϯ
    
    CVJMEHSBEMFͷઃఆ
    
    ָ͍͠,PUMJOϥΠϑͷ࢝·Γʂ

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    KotterKnife w,PUMJO൛#VUUFS,OJGF
    w࡞ऀ͸+BLF
    8IBSUPO͞Μ
    wಋೖ΍࢓૊Έղઆ͸ͪ͜ΒΛࢀর IUUQRJJUBDPNOHTX@UBSPJUFNTDEDEE

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    KotterKnife ࢖༻લ var button: Button? = null ! button =

    findViewById(R.id.button) as Button ! button?.setOnClickListener {...}
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    KotterKnife ࢖༻લ var button: Button? = null ! button =

    findViewById(R.id.button) as Button ! button?.setOnClickListener {...} "DUJWJUZͱ͔ͷϓϩύςΟ ຖ౓ͷpOE7JFX#Z*E
    ͦͯ͠Ωϟετʜ
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    KotterKnife ࢖༻ޙ var button: Button by bindView(R.id.button) ! button.setOnClickListener {...}

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    KotterKnife ࢖༻ޙ var button: Button by bindView(R.id.button) ! button.setOnClickListener {...}

    ϓϩύςΟ ಉ͡ CZΩʔϫʔυʹଓ͚ͯ
    3JECVUUPOΛόΠϯυ pOE7JFX#Z*EෆཁͰ
    ී௨ʹ࢖͑ΔΑ͏ʹͳͬͯΔ
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    Kotlin Android Extensions w"4
    ͱ*OUFMMJ+
    *%&" ͷϓϥάΠϯ
    wpOE7JFX#Z*EΛۦஞ͢Δ΍ͭ
    wνϡʔτϦΞϧ͸ͪ͜ΒΛࢀর IUUQLPUMJOMBOHPSHEPDTUVUPSJBMTBOESPJEQMVHJOIUNM

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    ࢖༻ྫ import kotlinx.android.synthetic.activity_main.button ! public class MainActivity: Activity() { override

    fun onCreate(savedInstaceState: Bundle?) { super.onCreate(savedInstaceState) setContentView(R.layout.activity_main) button.setOnClickListener {...}
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    Anko w͍ΖΜͳ%4-
    wओʹϨΠΞ΢τΛ૊Ή%4-
    wܕ҆શɺ؆ܿɾϦʔμϒϧɺ෦඼Խɾ ࠶ར༻ੑ
    wৄࡉ͸ͪ͜Β IUUQTHJUIVCDPN+FU#SBJOTBOLP

51. 51.

    None
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    ·ͱΊ w ,PUMJO͸ϓϩάϥϚʹ༏͍͠ʮݱ࣮ࢦ޲ʯݴޠ
    w "OESPJEͰ࢖͏ͱ޾ͤʹͳΕΔ͔΋

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    ͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠ Let’s enjoy Kotlin!