まだJavaで消耗してるの？Kotlinのすすめ

Cluex社主催 LT大会 発表資料

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1. ·ͩ+BWBͰফ໣ͯ͠Δͷʁ
 ɹɹɹɹɹͷ͢͢Ί
2. ࣗݾ঺հ w ాଜ
   ݠհʢ!,B[B,BHPʣ
   w גࣜձࣾΠάχεॴଐ
   w ࿀Ѫɾࠗ׆ϚονϯάαʔϏε ʮXJUIʯ։ൃϝϯόʔ
   w "OESPJE։ൃྺɿ͍͍ͩͨ೥͘Β͍
3. ࣗݾ঺հ
4. 8IBU`Tɹɹɹɹɹ
5. ɹɹɹɹɹͬͯԿʁ w +FU#SBJOT͕ࣾ։ൃͨ͠+BWB׬શޓ׵ݴޠ
   w *OUFMMJK
   *%&"΍3VCZ.JOFɺ1IQ4UPSNͳͲͷ*%&ʢ౷߹։ൃ؀ ڥʣΛ࡞ͬͯΔνΣίʹ͋Δձࣾ
   w ݱࡏͷόʔδϣϯ͸
   w Φʔϓϯιʔε "QBDIF
   ϥΠηϯε
6. "OESPJEͷୈҰݴޠʹʂ ࡢ೔ʢʂʣ(PPHMF
   *0
   ʹͯ
 "OESPJE։ൃͷୈҰڃݴޠʹͳΔͱൃද͞Ε·ͨ͠
7. ͷ
   ྑ͍ͱ͜Ζ
8. ಋೖͷෑډͷ௿͞ w (SBEMF΍.BWFOͳͲͷҰൠతͳϏϧυπʔϧΛಋ ೖ͍ͯ͠Ε͹͙͢ʹಋೖՄೳ
   w "OESPJEϓϩδΣΫτͳΒ΄΅͢΂ͯͷϓϩδΣΫτͰಋೖՄೳ
   w *OUFMMJK
   *%&"ͰϋΠϨϕϧͳαϙʔτ͕͞Ε͍ͯͯ +BWBˠ,PUMJOͷίϯόʔλʔ΋෇ଐ͞Ε͓ͯΓɺͦ Ε͕͔ͳΓ༏ल
   w "OESPJE
   4UVEJP΋*OUFMMJK
   *%&"ޓ׵Ͱ+FUCSBJOT͕ࣾ࡞͍ͬͯΔ
9. 4QSJOH
   'SBNFXPSL
   
10. ܕਪ࿦ ม਺͸+BWBͱҧ͍WBSͱ͍͏҉໧తͳܕએݴΛߦ͏ɻ
 ίʔυͷ࠷ޙʹʮʯΛ෇͚Δඞཁ͸ͳ͍ɻ
    w +BWB
    String value = new String("JavaͩΑʔʂ"); w ,PUMJO
    var value = String("KotlinͩΑʔʂ")
11. ܕਪ࿦ KBWBʹ͓͚ΔpOBMम০ࢠ͸,PUMJOͰWBMͱ͍͏ม਺એݴͰه ड़͢Δɻ
 WBMͰ͍͍ͱ͜ΖΛWBSͰهड़͢Δͱ*%&͔Βܯࠂ΋දࣔ͞Ε ΔͨΊKBWBΑΓpOBM͕పఈͰ͖Δʢؾ͕͢Δʣ
    w +BWB
    final String value = new String("JavaͩΑʔʂ"); w ,PUMJO
    val value = String("KotlinͩΑʔʂ")
12. ϥϜμࣜ ,PUMJOͰ͸ϥϜμ͕ࣜ࢖͑Δɻ
 "OESPJEͷϘλϯΠϕϯτ͸+BWBͰ͸ҎԼͷΑ͏ʹ͜͏ ॻ͕͘ɺɺɺ
    w +BWB +BWB
    Button button = new Button(this);
 button.setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View v) {
 System.out.print("Ϙλϯԡ͞Εͨʂ");
 }
 });
13. ϥϜμࣜ ,PUMJOͰ͸͜͏ɻ
    w ,PUMJO
    val button = Button(this)
 button.setOnClickListener {
 print("Ϙλϯԡ͞Εͨʂ")
 }

14. /VMM҆શ +BWBͩͱωετ͞Εͨਂ͍֊૚ͷม਺ΛऔΓग़ͦ͏ ͱ͢ΔͱҎԼͷΑ͏ͳίʔυʹͳΔɻ
 ͜Μͳ࣌ʹى͜Γ͕ͪͳͷ͕ɺɺ
    w +BWB
    ObjectD getObjectD(ObjectA objectA) {
 return objectA.getObjectB().getObjectC().getObjectD();
 }
15. /VMM҆શ NullPointerException
16. /VMM҆શ w +BWB
    ObjectD getObjectD(ObjectA objectA) {
 if (objectA != null) {
 ObjectB objectB = objectA.getObjectB();
 if (objectB != null) {
 ObjectC objectC = objectB.getObjectC();
 if (objectC != null) {
 return objectC.getObjectD();
 }
 }
 }
 return null;
 }

17. /VMM҆શ
18. /VMM҆શ ,PUMJOͰಉ౳ͷίʔυΛॻ͘৔߹ϫϯϥΠφʔͰॻ͚ Δ
    w ,PUMJO
    fun getObjectD(objectA: ObjectA?): ObjectD? {
 return objectA?.objectB?.objectC?.objectD
 }

19. /VMM҆શ w Λ͚ͭΔͱ/VMMΛ୅ೖͰ͖Δ
    var value: String? = null w Λ͚ͭͳ͍ͱ/VMMΛ୅ೖͰ͖ͳ͍
    var value: String = "hogehoge"
20. ֦ுؔ਺ w طଘͷΫϥεΠϯελϯεʹϝιουΛੜ΍͢͜ͱ ͕ग़དྷΔ
    fun Int.isEvenNumber(): Boolean {
 return (this % 2 == 0)
 } ˣ
    val counter: Int = 1
 val isEven = counter.isEvenNumber()
21. ͦͷଞʹ΋ʜ w ίϧʔνϯ
    w σϑΥϧτҾ਺
    w ετϦʔϜૢ࡞ؔ਺
    w σʔλΫϥε
    w ඇݕࠪྫ֎
    w KBWBTDSJQU΁ͷτϥΠϯεύΠϧ
    w ,PUMJO
    /BUJWF
    w FUD
22. ͷ
    l·ͩzྑ͘ͳ͍ͱ͜Ζ
23. +BWBͷ஌ࣝ͸ඞཁ w +BWBˡˠ,PUMJOͰ૬ޓʹ࢖͑Δ͕Ώ͑ʹݴޠΛ·ͨ ͙ࡍʹ֮͑ͯஔ͔ͳ͚Ε͹ͳΒͳ͍͓࡞๏͸ଟ͍ɻ
    w ಛʹϑϨʔϜϫʔΫ͕+BWBͰॻ͔Ε͍ͯΔ৔߹͸͔ ͳΓ஫ҙ͢Δඞཁ͕͋Γɻ
    w +BWBͷ஌͕ࣝͳ͍ͱͳͥΤϥʔ͕ൃੜ͍ͯ͠Δͷ ͔൑அ͕೉͍͜͠ͱ΋͋Δ
24. Ұ෦ͷϥΠϒϥϦ͸
 ͏·͘ಈ࡞͠ͳ͍ࣄ͕͋Δ w ΄ͱΜͲͷϥΠϒϥϦ͸໰୊ͳ͘ಈ࡞͢Δ͕ɺίʔ υͷࣗಈੜ੒Λߦ͏ϥΠϒϥϦ͸Ұ෦ಛघͳॻ͖ํ Λ͠ͳ͍ͱಈ࡞͠ͳ͍͜ͱ͕͋Δ
    w +BWBϥΠϒϥϦͩͱ,PUMJOతʹ͸৑௕ͳهड़Λͤ͟ ΔΛಘͳ͍͜ͱ͕͋Δ
25. ͷ
 ·ͱΊ
26. ·ͱΊ w +BWBΑΓݴޠ࢓্༷ʹ҆શ͔ͭ؆ܿʹॻ͚Δ
    w طଘͷ+BWBͱࠞࡏͰ͖ɺίϯόʔλʔ΋͋ΔͨΊ Ҡߦ͸ൺֱత༰қ
    w ॳֶऀ͸+BWB͔Βֶश͢΂͖
    w ໊લ͕ͳΜͱͳ͔͘Θ͍͍ʢ೔ຊਓฒײʣ
27. ͋Γ͕ͱ͏͍͟͝·ͨ͠