JavaからみたKotlin

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13. ਐΊํ ୯ମςετॻ͘ ίʔυॻ͘
14. 0CKFDU object KotlinObject { fun hello() : String { return "Hello Kotlin!" } fun hello2() = "Hello Kotlin!" } ˞γϯάϧτϯͰ͢ ,PUMJOͷ0CKFDU ˞IFMMP ͱIFMMP ͸CZUFDPEFʹ͢Δͱશ͘ಉ͡Ͱ͢
15. 0CKFDU import jp.a2kaido.skfj.KotlinObject as KO class KotlinObjectFromKotlinTest { @Test fun KotlinObject() { Assert.assertEquals("Hello Kotlin!", KO.hello()) Assert.assertEquals("Hello Kotlin!", KO.hello2()) } } ,PUMJO͔Βݟͨ৔߹
16. 0CKFDU public class KotlinObjectFromJavaTest { @Test public void KotlinObject() { Assert.assertEquals("Hello Kotlin!", KotlinObject.INSTANCE.hello()); Assert.assertEquals("Hello Kotlin!", KotlinObject.INSTANCE.hello2()); } } +BWB͔Βݟͨ৔߹
17. 0CKFDU public class KotlinObjectFromJavaTest { @Test public void KotlinObject() { Assert.assertEquals("Hello Kotlin!", KotlinObject.INSTANCE.hello()); Assert.assertEquals("Hello Kotlin!", KotlinObject.INSTANCE.hello2()); } } +BWB͔Βݟͨ৔߹ ˞*/45"/$&ʜ
18. 0CKFDU ,PUMJOͷ0CKFDU
     object KotlinObject2 { @JvmStatic fun hello() : String { return "Hello Kotlin!" } @JvmStatic fun hello2() = "Hello Kotlin!" }
19. 0CKFDU +BWB͔Βݟͨ৔߹ public class KotlinObjectFromJavaTest { @Test public void KotlinObject() { Assert.assertEquals("Hello Kotlin!", KotlinObject.INSTANCE.hello()); Assert.assertEquals("Hello Kotlin!", KotlinObject.INSTANCE.hello2()); } @Test public void KotlinObject2() { Assert.assertEquals("Hello Kotlin!", KotlinObject2.hello()); Assert.assertEquals("Hello Kotlin!", KotlinObject2.hello2()); } } ,PUMJO0CKFDUHFU*OTUBODF IFMMP ͱॻ͖͍ͨ
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    GVODUJPO fun hello() : String { return "Hello Kotlin!" } ,PUMJO'VODUJPOLU ˞Ϋϥεʹଐ͞ͳ͍ؔ਺
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    GVODUJPO ,PUMJO͔Βݟͨ৔߹ class KotlinFunctionFromKotlinTest { @Test fun KotlinFunction() { Assert.assertEquals("Hello Kotlin!", hello()) } }
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    GVODUJPO +BWB͔Βݟͨ৔߹ public class KotlinFunctionFromJavaTest { @Test public void KotlinFunction() { Assert.assertEquals("Hello Kotlin!", KotlinFunctionKt.hello()); } } ,PUMJO'VODUJPO,Uͱ͍͏Ϋϥε͕Ͱ͖ͯΔ ͦͷΫϥεʹTUBUJDϝιου͕ੜ͑ͯΔ
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    GVODUJPO fun hello() : String { return "Hello Kotlin!" } ,PUMJO'VODUJPOLU ,PUMJO'VODUJPO,Uͱ͍͏໊લ͕ؾ࣋ͪѱ͍ͷͰɺ
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     @file:JvmName("KotlinFunctionRefine") package jp.a2kaido.skfj.function fun helloRefine() : String { return "Hello Kotlin!" } ,PUMJO'VODUJPO3FpOFLU ໊લΛ͚ͭΔ
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    GVODUJPO +BWB͔Βݟͨ৔߹ public class KotlinFunctionFromJavaTest { @Test public void KotlinFunction() { Assert.assertEquals("Hello Kotlin!", KotlinFunctionKt.hello()); } @Test public void KotlinObjectRefine() { Assert.assertEquals("Hello Kotlin!", KotlinFunctionRefine.helloRefine()); } } ,Uͷ··ͩͱؾ࣋ͪѱ͍ͷͰΞϊςʔγϣϯͰ
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28. &YUFOTJPO ,PUMJOͷ&YUFOTJPO fun String.hello() = "Hello Kotlin!" 4USJOH&YUFOTJPOLU @file:JvmName("String") package jp.a2kaido.skfj.extension fun String.helloRefine() = "Hello Kotlin!" 4USJOH&YUFOTJPO3FpOFLU
29. &YUFOTJPO ,PUMJO͔Βݟͨ৔߹ class StringExtensionFromKotlinTest { @Test fun StringExtension() { Assert.assertEquals("Hello Kotlin!", "hoge".hello()) } @Test fun StringExtensionRefine() { Assert.assertEquals("Hello Kotlin!", "hoge".helloRefine()) } }
30. &YUFOTJPO +BWB͔Βݟͨ৔߹ public class StringExtensionFromJavaTest { @Test public void StringExtension() { Assert.assertEquals("Hello Kotlin!", StringExtensionKt.hello("hoge")); } @Test public void StringExtensionRefile() { Assert.assertEquals("Hello Kotlin!", String.helloRefine("hoge")); } } 4USJOH&YUFOTJPO,Uͱ͍͏Ϋϥε͕Ͱ͖ͯΔ ϨγʔόʔΛҾ਺Ͱड͚औΔ ݺͼग़ͤΔ͚Ͳʜ&YUFOTJPOͷ͝ར༻͸ܭըతʹ
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32. %FGBVMU
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    "SHVNFOU class KotlinDefaultArgument { fun hello(s : String = "Kotlin") = "Hello $s!" } class KotlinDefaultArgumentRefine { @JvmOverloads fun hello(s : String = "Kotlin") = "Hello $s!" }
33. %FGBVMU
    "SHVNFOU ,PUMJO͔Βݟͨ৔߹ class KotlinDefaultArgumentFromKotlinTest { @Test fun kotlinDefaultArgument() { val target = KotlinDefaultArgument() Assert.assertEquals("Hello Kotlin!", target.hello()) Assert.assertEquals("Hello Java!", target.hello("Java")) } @Test fun kotlinDefaultArgumentRefine() { val target = KotlinDefaultArgumentRefine() Assert.assertEquals("Hello Kotlin!", target.hello()) Assert.assertEquals("Hello Java!", target.hello("Java")) } }
34. %FGBVMU
    "SHVNFOU +BWB͔Βݟͨ৔߹ public class KotlinDefaultArgumentFromJavaTest { @Test public void KotlinDefaultArgument() { KotlinDefaultArgument target = new KotlinDefaultArgument(); // cannot compile // Assert.assertEquals("Hello Kotlin!", target.hello()); Assert.assertEquals("Hello Java!", target.hello("Java")); } @Test public void KotlinDefaultArgumentRefine() { KotlinDefaultArgumentRefine target = new KotlinDefaultArgumentRefine(); Assert.assertEquals("Hello Kotlin!", target.hello()); Assert.assertEquals("Hello Java!", target.hello("Java")); } } @JvmOverloadsΛ͚ͭͳ͍ͱҾ਺ͳ͠ͷݺͼग़͕͠Ͱ͖ͳ͍
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36. %FGBVMU
    *NQMFNFOUBUJPO interface DefaultInterface { fun hello() = "Hello Kotlin!" fun hello2() : String } ,PUMJOͷ%FGBVMU
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    *NQMFNFOUBUJPO class DefaultInterfaceKotlinImpl : DefaultInterface { override fun hello2() = "Hello Kotlin!" } ,PUMJOͰ࣮૷
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    *NQMFNFOUBUJPO public class DefaultInterfaceJavaImpl implements DefaultInterface { @NotNull @Override public String hello() { // ࣮૷ඞਢ return DefaultImpls.hello(this); // DefaultImpls͕ੜ͑ͯΔ } @NotNull @Override public String hello2() { return "Hello Kotlin!"; } } +BWBͰ࣮૷ ஌Βͳ͍ͱແཧήʔɻσϑΥϧτΛແࢹ࣮ͯ͠૷ͦ͠͏ɻ
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