JavaからみたKotlin

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1. +BWB͔Βݟͨ
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2. w ϓϩϑΟʔϧ
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3. ೋ֊ಊว ʹ͔͍Ͳ͏͋·Ͷ
   
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4. ,PUMJOͷ͕͜͜޷͖
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5. ,PUMJOͷ͕͜͜޷͖
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7. ,PUMJOָ͍͠ʂ
   

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8. ,PUMJOָ͍͠ʂ
   

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9. ͚Ͳɺ+BWBͷؾ࣋ͪ
   ΋ߟ͑ͯ͋͛Αʁ
   

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10. +BWB͔Βݟͨ
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11. w ,PUMJOͱ+BWBͷޓ׵ੑ
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12. 0CKFDU
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13. ਐΊํ
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14. 0CKFDU
    object KotlinObject {
    fun hello() : String {
    return "Hello Kotlin!"
    }
    fun hello2() = "Hello Kotlin!"
    }
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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৔߹
    

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16. 0CKFDU
    public class KotlinObjectFromJavaTest {
    @Test
    public void KotlinObject() {
    Assert.assertEquals("Hello Kotlin!", KotlinObject.INSTANCE.hello());
    Assert.assertEquals("Hello Kotlin!", KotlinObject.INSTANCE.hello2());
    }
    }
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17. 0CKFDU
    public class KotlinObjectFromJavaTest {
    @Test
    public void KotlinObject() {
    Assert.assertEquals("Hello Kotlin!", KotlinObject.INSTANCE.hello());
    Assert.assertEquals("Hello Kotlin!", KotlinObject.INSTANCE.hello2());
    }
    }
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18. 0CKFDU
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    object KotlinObject2 {
    @JvmStatic
    fun hello() : String {
    return "Hello Kotlin!"
    }
    @JvmStatic
    fun hello2() = "Hello Kotlin!"
    }
    

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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());
    }
    }
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20. 0CKFDU
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21. 5PQMFWFMGVODUJPO
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    fun hello() : String {
    return "Hello Kotlin!"
    }
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22. 5PQMFWFMGVODUJPO
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    class KotlinFunctionFromKotlinTest {
    @Test
    fun KotlinFunction() {
    Assert.assertEquals("Hello Kotlin!", hello())
    }
    }
    

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23. 5PQMFWFMGVODUJPO
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    public class KotlinFunctionFromJavaTest {
    @Test
    public void KotlinFunction() {
    Assert.assertEquals("Hello Kotlin!", KotlinFunctionKt.hello());
    }
    }
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24. 5PQMFWFMGVODUJPO
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    fun hello() : String {
    return "Hello Kotlin!"
    }
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25. 5PQMFWFMGVODUJPO
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    @file:JvmName("KotlinFunctionRefine")
    package jp.a2kaido.skfj.function
    fun helloRefine() : String {
    return "Hello Kotlin!"
    }
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26. 5PQMFWFMGVODUJPO
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    public class KotlinFunctionFromJavaTest {
    @Test
    public void KotlinFunction() {
    Assert.assertEquals("Hello Kotlin!", KotlinFunctionKt.hello());
    }
    @Test
    public void KotlinObjectRefine() {
    Assert.assertEquals("Hello Kotlin!", KotlinFunctionRefine.helloRefine());
    }
    }
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27. 0CKFDU
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28. &YUFOTJPO
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    fun String.hello() = "Hello Kotlin!"
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    @file:JvmName("String")
    package jp.a2kaido.skfj.extension
    fun String.helloRefine() = "Hello Kotlin!"
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29. &YUFOTJPO
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    class StringExtensionFromKotlinTest {
    @Test
    fun StringExtension() {
    Assert.assertEquals("Hello Kotlin!", "hoge".hello())
    }
    @Test
    fun StringExtensionRefine() {
    Assert.assertEquals("Hello Kotlin!", "hoge".helloRefine())
    }
    }
    

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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"));
    }
    }
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31. 0CKFDU
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32. %FGBVMU"SHVNFOU
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    class KotlinDefaultArgument {
    fun hello(s : String = "Kotlin") = "Hello $s!"
    }
    class KotlinDefaultArgumentRefine {
    @JvmOverloads
    fun hello(s : String = "Kotlin") = "Hello $s!"
    }
    

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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"))
    }
    }
    

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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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35. 0CKFDU
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36. %FGBVMU*NQMFNFOUBUJPO
    interface DefaultInterface {
    fun hello() = "Hello Kotlin!"
    fun hello2() : String
    }
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37. %FGBVMU*NQMFNFOUBUJPO
    class DefaultInterfaceKotlinImpl : DefaultInterface {
    override fun hello2() = "Hello Kotlin!"
    }
    ,PUMJOͰ࣮૷
    

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38. %FGBVMU*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!";
    }
    }
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39. 0CKFDU
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40. w ,PUMJOָ͍͠ʂ
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41. w αϯϓϧίʔυ
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42. ͝੩ௌ͋Γ͕ͱ͏

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