Generating Kotlin Code (KotlinConf 2017)

Kotlin provides simpler options than traditional Java patterns like builders and factories often found in the generated code. By using Kotlin to generate an API, you can not only create a pleasant experience from both languages, but also unlock the possibility of targeting native and JS. This talk will cover the tools needed to generate Kotlin code and also the features available in Kotlin that can improve your generated code.

Video: coming soon

Transcript

1. Kotlin Code Generation Alec Strong & Jake Wharton
2. public final class User { private final String firstName; private final String lastName; private final int age; public User(String firstName, String lastName, int age) { this.firstName = firstName; this.lastName = lastName; this.age = age; } public String getFirstName() { return firstName; } public String getLastName() { return lastName; } public int getAge() { return age; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; User user = (User) o; return age == user.age && Objects.equals(firstName, user.firstName) && Objects.equals(lastName, user.lastName); } @Override public int hashCode() { return Objects.hash(firstName, lastName, age); } @Override public String toString() { return "User{" + "firstName='" + firstName + '\'' + ", lastName='" + lastName + '\'' + ", age=" + age + '}'; } } data class User( val firstName: String, val lastName: String, val age: Int )
3. Bytecode
4. Protocol Buffers
5. Protocol Buffers SQL
6. Protocol Buffers SQL Swagger
7. Protocol Buffers SQL Swagger Android XML
8. Protocol Buffers SQL Swagger Android XML YAML
9. SQL Swagger Android XML YAML Mirrors/Elements
10. Swagger Android XML YAML Mirrors/Elements PSI
11. Android XML YAML Mirrors/Elements PSI UAST
12. YAML Mirrors/Elements PSI UAST ???
13. Protocol Buffers SQL Swagger Android XML YAML Mirrors/Elements PSI UAST ???
14. Protocol Buffers
15. syntax = "proto2"; package com.sample; message Ogre { required string name = 1; repeated int32 layers = 2; optional string swamp = 3; }
16. public final String name; public final List<Integer> layers; public final String swamp; public Ogre(String name, List<Integer> layers, String swamp) { this(name, layers, swamp, ByteString.EMPTY); } public Ogre(String name, List<Integer> layers, String swamp, ByteString unknownFields) { super(ADAPTER, unknownFields); this.name = name; this.layers = Internal.immutableCopyOf("layers", layers); this.swamp = swamp; }
17. public final String name; public final List<Integer> layers; public final String swamp; public Ogre(String name, List<Integer> layers, String swamp) { this(name, layers, swamp, ByteString.EMPTY); } public Ogre(String name, List<Integer> layers, String swamp, ByteString unknownFields) { super(ADAPTER, unknownFields); this.name = name; this.layers = Internal.immutableCopyOf("layers", layers); this.swamp = swamp; } public final String name; public final List<Integer> layers; public final String swamp; this.name = name; this.layers = Internal.immutableCopyOf("layers", layers); this.swamp = swamp;
18. public final String name; public final List<Integer> layers; public final String swamp; public Ogre(String name, List<Integer> layers, String swamp) { this(name, layers, swamp, ByteString.EMPTY); } public Ogre(String name, List<Integer> layers, String swamp, ByteString unknownFields) { super(ADAPTER, unknownFields); this.name = name; this.layers = Internal.immutableCopyOf("layers", layers); this.swamp = swamp; } ByteString.EMPTY ByteString unknownFields
19. public final String name; public final List<Integer> layers; public final String swamp; public Ogre(String name, List<Integer> layers, String swamp) { this(name, layers, swamp, ByteString.EMPTY); } public Ogre(String name, List<Integer> layers, String swamp, ByteString unknownFields) { super(ADAPTER, unknownFields); this.name = name; this.layers = Internal.immutableCopyOf("layers", layers); this.swamp = swamp; } Internal.immutableCopyOf("layers", layers)
20. public final String name; public final List<Integer> layers; public final String swamp; public Ogre(String name, List<Integer> layers, String swamp) { this(name, layers, swamp, ByteString.EMPTY); } public Ogre(String name, List<Integer> layers, String swamp, ByteString unknownFields) { super(ADAPTER, unknownFields); this.name = name; this.layers = Internal.immutableCopyOf("layers", layers); this.swamp = swamp; } String name String swamp String name String swamp String name String swamp
21. public final String name; public final List<Integer> layers; public final String swamp; public Ogre(String name, List<Integer> layers, String swamp) { this(name, layers, swamp, ByteString.EMPTY); } public Ogre(String name, List<Integer> layers, String swamp, ByteString unknownFields) { super(ADAPTER, unknownFields); this.name = name; this.layers = Internal.immutableCopyOf("layers", layers); this.swamp = swamp; }
22. class Ogre @JvmOverloads constructor( val name: String, val layers: List<Int>, val swamp: String?, unknownFields: ByteString = ByteString.EMPTY ) : Message<Ogre, Ogre.Builder>(ADAPTER, unknownFields)
23. class Ogre @JvmOverloads constructor( val name: String, val layers: List<Int>, val swamp: String?, unknownFields: ByteString = ByteString.EMPTY ) : Message<Ogre, Ogre.Builder>(ADAPTER, unknownFields) val name: String, val layers: List<Int>, val swamp: String?, Ogre shrek = new Ogre("Shrek", Arrays.asList(1, 2), null); System.out.println(shrek.getSwamp()); s
24. class Ogre @JvmOverloads constructor( @JvmField val name: String, @JvmField val layers: List<Int>, @JvmField val swamp: String?, unknownFields: ByteString = ByteString.EMPTY ) : Message<Ogre, Ogre.Builder>(ADAPTER, unknownFields) @JvmField val name: String, @JvmField val layers: List<Int>, @JvmField val swamp: String?, Ogre shrek = new Ogre("Shrek", Arrays.asList(1, 2), null); System.out.println(shrek.swamp); Se
25. override fun equals(other: Any?): Boolean { if (other === this) return true if (other !is OgreKt) return false val o = other as OgreKt? return (unknownFields() == o!!.unknownFields() && name == o.name && layers == o.layers && Internal.equals(swamp, o.swamp)) } override fun hashCode(): Int { var result = super.hashCode if (result == 0) { result = unknownFields().hashCode() result = result * 37 + name.hashCode() result = result * 37 + layers.hashCode() result = result * 37 + (swamp?.hashCode() ?: 0) super.hashCode = result } return result } override fun toString(): String { val builder = StringBuilder() builder.append(", name=").append(name) if (!layers.isEmpty()) builder.append(", layers=").append(layers) if (swamp != null) builder.append(", swamp=").append(swamp) return builder.replace(0, 2, "Ogre{").append('}').toString() }
26. class Ogre @JvmOverloads constructor( @JvmField val name: String, @JvmField val layers: List<Int>, @JvmField val swamp: String?, unknownFields: ByteString = ByteString.EMPTY ) : Message<Ogre, Ogre.Builder>(ADAPTER, unknownFields)
27. data class Ogre @JvmOverloads constructor( @JvmField val name: String, @JvmField val layers: List<Int>, @JvmField val swamp: String?, unknownFields: ByteString = ByteString.EMPTY ) : Message<Ogre, Ogre.Builder>(ADAPTER, unknownFields)
28. data class Ogre @JvmOverloads constructor( @JvmField val name: String, @JvmField val layers: List<Int>, @JvmField val swamp: String?, unknownFields: ByteString = ByteString.EMPTY ) : Message<Ogre, Ogre.Builder>(ADAPTER, unknownFields) data class Ogre unknownFields: ByteString = ByteString.EMPTY
29. data class Ogre @JvmOverloads constructor( @JvmField val name: String, @JvmField val layers: List<Int>, @JvmField val swamp: String?, private val unknownFields: ByteString = ByteString.EMPTY ) : Message<Ogre, Ogre.Builder>(ADAPTER, unknownFields) data class Ogre private val unknownFields: ByteString = ByteString.EMPTY
30. class Ogre @JvmOverloads constructor( @JvmField val name: String, @JvmField val layers: List<Int>, @JvmField val swamp: String?, unknownFields: ByteString = ByteString.EMPTY ) : Message<Ogre, Ogre.Builder>(ADAPTER, unknownFields)
31. public static final class Builder extends Message.Builder<Ogre, Builder> { public String name; public List<Integer> layers; public String swamp; public Builder() { layers = Internal.newMutableList(); } public Builder name(String name) { this.name = name; return this; } public Builder layers(List<Integer> layers) { Internal.checkElementsNotNull(layers); this.layers = layers; return this; } public Builder swamp(String swamp) { this.swamp = swamp; return this; } @Override public Ogre build() { if (name == null) { throw Internal.missingRequiredFields(name, "name"); } return new Ogre(name, layers, swamp, super.buildUnknownFields()); } }
32. public static final class Builder extends Message.Builder<Ogre, Builder> { public String name; public List<Integer> layers; public String swamp; public Builder() { layers = Internal.newMutableList(); } public Builder name(String name) { this.name = name; return this; } public Builder layers(List<Integer> layers) { Internal.checkElementsNotNull(layers); this.layers = layers; return this; } public Builder swamp(String swamp) { this.swamp = swamp; return this; } @Override public Ogre build() { if (name == null) { throw Internal.missingRequiredFields(name, "name"); } return new Ogre(name, layers, swamp, super.buildUnknownFields()); } } Internal.checkElementsNotNull(layers); if (name == null) { throw Internal.missingRequiredFields(name, "name"); }
33. public static final class Builder extends Message.Builder<Ogre, Builder> { public String name; public List<Integer> layers; public String swamp; public Builder() { layers = Internal.newMutableList(); } public Builder name(String name) { this.name = name; return this; } public Builder layers(List<Integer> layers) { Internal.checkElementsNotNull(layers); this.layers = layers; return this; } public Builder swamp(String swamp) { this.swamp = swamp; return this; } @Override public Ogre build() { if (name == null) { throw Internal.missingRequiredFields(name, "name"); } return new Ogre(name, layers, swamp, super.buildUnknownFields()); } }
34. class Ogre @JvmOverloads constructor( @JvmField val name: String, @JvmField val layers: List<Int> @JvmField val swamp: String? unknownFields: ByteString = ByteString.EMPTY ) : Message<Ogre, Ogre.Builder>(ADAPTER, unknownFields) @JvmField val name: String, @JvmField val layers: List<Int> = emptyList(), @JvmField val swamp: String? = null,
35. val shrek = Ogre( name = "shrek", layers = listOf(1, 2), swamp = null )
36. Ogre shrek = new Ogre();
37. Ogre shrek = new Ogre("Shrek", Arrays.asList(1, 2), "Shrek");
38. Java Interop
39. class Ogre( @JvmField val name: String, @JvmField val layers: List<Int> = emptyList(), @JvmField val swamp: String? = null ) interface @JvmField val name: String, @JvmField val layers: List<Int> = emptyList(), @JvmField val swamp: String? = null
40. interface Ogre { val name: String val layers: List<Int> val swamp: String? }
41. interface Ogre { val name: String val layers: List<Int> val swamp: String? } shrek.getLayers();
42. inline fun <reified T> Ogre.findFriendOfType(): T? { for (friend in friends()) { if (friend is T) return friend } return null }
43. inline fun <reified T> Ogre.findFriendOfType(): T? { for (friend in friends()) { if (friend is T) return friend } return null }
 
 shrek.findFriendOfType<Donkey>()
44. inline fun <reified T> Ogre.findFriendOfType(): T? { for (friend in friends()) { if (friend is T) return friend } return null }
 
 shrek.findFriendOfType<Donkey>() shrek.<Donkey>findFriendOfType();
45. inline fun <reified T> Ogre.findFriendOfType(): T? { for (friendain friends()) { if (friend is T) return friend }Y returnbnull }Z
46. fun <T> Ogre.findFriendOfType(type: Class<T>): T? { for (friend in friends()) { if (type.isInstance(friend)) return friend as T? }B return null }A inline fun <reified T> Ogre.findFriendOfType(): T? { for (friendain friends()) { if (friend is T) return friend }Y returnbnull }Z findFriendOfType( ::class.java)
47. fun <T> Ogre.findFriendOfType(type: Class<T>): T? { for (friend in friends()) { if (type.isInstance(friend)) return friend as T? }B return null }A inline fun <reified T> Ogre.findFriendOfType(): T? { returnbfindFriendOfType(T::class.java) }Z
48. interface SwampChangedListener { fun swampChanged(newSwamp: String) } fun addSwampChangedListener(listener: SwampChangedListener) = …
49. interface SwampChangedListener { fun swampChanged(newSwamp: String) }A fun addSwampChangedListener(listener: SwampChangedListener) = … shrek.addSwampChangedListener(new SwampChangedListener() { @Override public void swampChanged(@NotNull String newSwamp) {P System.out.println("What are you doing in " + newSwamp); } });
50. interface SwampChangedListener { fun swampChanged(newSwamp: String) }A fun addSwampChangedListener(listener: SwampChangedListener) = … shrek.addSwampChangedListener(newSwamp -> {P System.out.println("What are you doing in " + newSwamp); });
51. interface SwampChangedListener { fun swampChanged(newSwamp: String) } fun addSwampChangedListener(listener: SwampChangedListener) = …
52. interface SwampChangedListener { fun swampChanged(newSwamp:(String): Unit } fun addSwampChangedListener(listener: SwampChangedListener) = … shrek.addSwampChangedListener(object : SwampChangedListener { override fun swampChanged(newSwamp: String) { System.out.println("What are you doing in $newSwamp") } }) KT-7770
53. fun addSwampChangedListener(listener: (String) -> Unit) = …
54. fun addSwampChangedListener(listener: (String) -> Unit) = … shrek.addSwampChangedListener { newSwamp -> System.out.println("What are you doing in $newSwamp") }
55. fun addSwampChangedListener(listener: (String) -> Unit) = … shrek.addSwampChangedListener { newSwamp -> System.out.println("What are you doing in $newSwamp") } shrek.addSwampChangedListener(newSwamp -> { System.out.println("What are you doing in " + newSwamp); return Unit.INSTANCE; }); KT-21018
56. fun addSwampChangedListener(listener: SwampChangedListener) = … public interface SwampChangedListener { void swampChanged(String newSwamp); }Z
57. fun addSwampChangedListener(listener: SwampChangedListener) = … shrek.addSwampChangedListener(SwampChangedListener { newSwamp -> System.out.println("What are you doing in $newSwamp") }) public interface SwampChangedListener { void swampChanged(String newSwamp); }Z
58. fun addSwampChangedListener(listener: SwampChangedListener) = … public interface SwampChangedListener { void swampChanged(String newSwamp); }Z shrek.addSwampChangedListener(newSwamp -> { System.out.println("What are you doing in " + newSwamp); }); shrek.addSwampChangedListener(SwampChangedListener { newSwamp -> System.out.println("What are you doing in $newSwamp") })
59. sealed class Optional<T : Any> data class Some<T : Any>(val value: T): Optional<T>() object None : Optional<Nothing>()
60. sealed class Optional<T : Any> data class Some<T : Any>(val value: T): Optional<T>() object None : Optional<Nothing>() fun <T : Any> T?.asOptional() = if (this == null) None else Some(this)
61. @file:JvmName("Optionals") sealed class Optional<T : Any> data class Some<T : Any>(val value: T): Optional<T>() object None : Optional<Nothing>() @JvmName("ofNullable") fun <T : Any> T?.asOptional() = if (this == null) None else Some(this)
62. sealed class Optional<T : Any> { companion object { @JvmName("ofNullable") @JvmStatic fun <T : Any> T?.asOptional() = if (this == null) None else Some(this) }Y }Z data class Some<T : Any>(val value: T): Optional<T>() object None : Optional<Nothing>() KT-15286 @file:JvmName("Optionals")
63. sealed class Optional<T : Any> { companion object { @JvmStatic fun <T : Any> ofNullable(value: T?) = value.asOptional() }Y }Z data class Some<T : Any>(val value: T): Optional<T>() object None : Optional<Nothing>() fun <T : Any> T?.asOptional() = if (this == null) None else Some(this) KT-15286 @JvmName
64. @file:JvmName("-Optionals") sealed class Optional<T : Any> { companion object { @JvmStatic fun <T : Any> ofNullable(value: T?) = value.asOptional() }Y }Z data class Some<T : Any>(val value: T): Optional<T>() object None : Optional<Nothing>() fun <T : Any> T?.asOptional() = if (this == null) None else Some(this) KT-15286
65. class Foo ( val bar: Nothing, val listBar: List<Nothing> )
66. class Foo ( val bar: Nothing, val listBar: List<Nothing> ) Void bar = foo.getBar(); List listBar = foo.getListBar();
67. KotlinPoet
68. Type
69. Type Class
70. Type Class Parameterized Type
71. Type String Map<String,Int>
72. val stringClass: KClass<String> = String::class
73. val stringClass: KClass<String> = String::class val stringName: ClassName = stringClass.asClassName()
74. val stringClass: KClass<String> = String::class val stringName: ClassName = stringClass.asClassName() import kotlin.String val foo: String = ""
75. val stringClass: KClass<String> = String::class val stringName: ClassName = stringClass.asClassName() import kotlin.String val foo: String = "" class String
76. val stringClass: KClass<String> = String::class val stringName: ClassName = stringClass.asClassName() class String { val foo: kotlin.String = "" }
77. val stringClass: KClass<String> = String::class val stringName: ClassName = stringClass.asClassName()
78. val stringClass: KClass<String> = String::class val stringName: ClassName = stringClass.asClassName() val mapStringToInt = ParameterizedTypeName.get( Map::class.asTypeName(), stringName, Int::class.asTypeName())
79. val stringClass: KClass<String> = String::class val stringName: ClassName = stringClass.asClassName() val mapStringToInt = ParameterizedTypeName.get( Map::class.asTypeName(), stringName, Int::class.asTypeName()) val nullableMap = mapStringToInt.asNullable()
80. val foo = PropertySpec.builder("foo", String::class) .initializer("%S", "foo") .build()
81. val foo = PropertySpec.builder("foo", String::class) .initializer("%S", "foo") .build() String::class
82. val foo = PropertySpec.builder("foo", String::class) .initializer("%S", "foo") .build() "%S", "foo"
83. val foo = PropertySpec.builder("foo", String::class) .initializer("%S", "foo") .build()
84. val foo = PropertySpec.builder("foo", String::class) .initializer("%S", "foo") .build() println(foo) val foo: kotlin.String = "foo"X
85. val foo = PropertySpec.builder("foo", String::class) .initializer("%S", "foo\tbar") .build() println(foo) val foo: kotlin.String = "foo\tbar"X
86. val foo = PropertySpec.builder("foo", String::class) .initializer("%S", "foo\tbar") .build() println(foo) val foo: kotlin.String = "foo\tbar"X kotlin.String
87. val foo = PropertySpec.builder("foo", String::class) .initializer("%S", "foo\tbar") .build() val file = FileSpec.builder("com.example", "KotlinConf.kt") .addProperty(foo) .build() println(file) package com.example import kotlin.String val foo: String = "foo\tbar"X foo
88. PropertySpec.builder("foo", String::class) .initializer("%S", "foo\tbar") .build() package com.example import kotlin.String val foo: String = "foo\tbar"X
89. FunSpec.builder("main") .addParameter("args", String::class, VARARG) .build() package com.example import kotlin.String fun main(vararg args: String) { }
90. TypeSpec.classBuilder("User") .addModifiers(DATA) .build() package com.example data class User
91. TypeSpec.classBuilder("User") .addModifiers(DATA) .build() package com.example data class User
92. TypeSpec.classBuilder("User") .addModifiers(DATA) .addProperty(PropertySpec.builder("name", String::class).build()) .build()Z package com.example data class User {Y val name: String }X
93. TypeSpec.classBuilder("User") .addModifiers(DATA) .addProperty(PropertySpec.builder("name", String::class).build()) .primaryConstructor(FunSpec.constructorBuilder() .addParameter("name", String::class) .build())A .build()Z package com.example data class User(name: String)G{Y val name: String }X
94. name: String TypeSpec.classBuilder("User") .addModifiers(DATA) .addProperty(PropertySpec.builder("name", String::class) .initializer("name") .build())B .primaryConstructor(FunSpec.constructorBuilder() .addParameter("name", String::class) .build())A .build() package com.example data class User(val name: String)G
95. TypeSpec.classBuilder("User") .addModifiers(DATA) .addProperty(PropertySpec.builder("name", String::class) .initializer("name.toLowerCase()") .build())B .primaryConstructor(FunSpec.constructorBuilder() .addParameter("name", String::class) .build())A .build() package com.example data class User(name: String)G{ val name: String = name.toLowerCase() }X
96. FunSpec.builder("seconds") .receiver(Long::class) .returns(Duration::class) .addStatement("return %T.ofSeconds(this)", Duration::class) .build() package com.example import java.time.Duration import kotlin.Long fun Long.seconds(): Duration = Duration.ofSeconds(this)
97. FunSpec.builder("seconds") .receiver(Long::class) .returns(Duration::class) .addStatement("require(this >= 0L)") .addStatement("return %T.ofSeconds(this)", Duration::class) .build() package com.example import java.time.Duration import kotlin.Long fun Long.seconds(): Duration { require(this >= 0L) return Duration.ofSeconds(this) }
98. FunSpec.builder("seconds") .receiver(Long::class) .returns(Duration::class) .addStatement("require(this >= 0L)") .addStatement("return %T.ofSeconds(this)", Duration::class) .build()
99. val longSeconds = FunSpec.builder("seconds") .receiver(Long::class) .returns(Duration::class) .addStatement("require(this >= 0L)") .addStatement("return %T.ofSeconds(this)", Duration::class) .build()
100. val longSeconds = FunSpec.builder("seconds") .receiver(Long::class) .returns(Duration::class) .addStatement("require(this >= 0L)") .addStatement("return %T.ofSeconds(this)", Duration::class) .build() FunSpec.builder("main") .addParameter("args", String::class, VARARG) .addStatement("println(%L.%N())", 2L, longSeconds) .build()
101. val longSeconds = FunSpec.builder("seconds") .receiver(Long::class) .returns(Duration::class) .addStatement("require(this >= 0L)") .addStatement("return %T.ofSeconds(this)", Duration::class) .build() FunSpec.builder("main") .addParameter("args", String::class, VARARG) .addStatement("println(%L.%N())", 2L, longSeconds) .build() %N longSeconds
102. val longSeconds = FunSpec.builder("seconds") .receiver(Long::class) .returns(Duration::class) .addStatement("require(this >= 0L)") .addStatement("return %T.ofSeconds(this)", Duration::class) .build() FunSpec.builder("main") .addParameter("args", String::class, VARARG) .addStatement("println(%L.%N())", 2L, longSeconds) .build() fun main(vararg args: String) { println(2L.seconds()) }
103. val code = CodeBlock.builder()
104. val code = CodeBlock.builder() code.addStatement("val foo = %T.MIN_VALUE", Int::class)
105. val code = CodeBlock.builder() code.addStatement("val foo = %T.MIN_VALUE", Int::class) code.add("val bar = ") when (answer) { YES -> code.add("0L") NO -> code.add("%T.MIN_VALUE", Int::class) } code.add(".toString()\n")
106. val code = CodeBlock.builder() code.addStatement("val foo = %T.MIN_VALUE", Int::class) code.add("val bar = ") when (answer) { YES -> code.add("0L") NO -> code.add("%T.MIN_VALUE", Int::class) } code.add(".toString()\n") code.beginControlFlow("if (bar.isEmpty())") .addStatement("println(%S)", "Empty!") .nextControlFlow("else") .addStatement("println(bar)") .endControlFlow()
107. val intMin = CodeBlock.of("%T.MIN_VALUE", Int::class) val intMax = CodeBlock.of("%T.MAX_VALUE", Int::class) val longMin = CodeBlock.of("%T.MIN_VALUE", Long::class) val longMax = CodeBlock.of("%T.MAX_VALUE", Long::class) val values = listOf(intMin, intMax, longMin, longMax)
108. val intMin = CodeBlock.of("%T.MIN_VALUE", Int::class) val intMax = CodeBlock.of("%T.MAX_VALUE", Int::class) val longMin = CodeBlock.of("%T.MIN_VALUE", Long::class) val longMax = CodeBlock.of("%T.MAX_VALUE", Long::class) val values = listOf(intMin, intMax, longMin, longMax) // elsewhere val list = values.joinToCode(prefix = "listOf(", suffix = ")")
109. val intMin = CodeBlock.of("%T.MIN_VALUE", Int::class) val intMax = CodeBlock.of("%T.MAX_VALUE", Int::class) val longMin = CodeBlock.of("%T.MIN_VALUE", Long::class) val longMax = CodeBlock.of("%T.MAX_VALUE", Long::class) val values = listOf(intMin, intMax, longMin, longMax) // elsewhere val list = values.joinToCode(prefix = "listOf(", suffix = ")") listOf(Int.MIN_VALUE, Int.MAX_VALUE, Long.MIN_VALUE, Long.MAX_VALUE)
110. inline fun <reified T, R : CharSequence> (String.() -> R).crazy(noinline foo: T.(R?) -> Unit) where T : Runnable, T : Closeable = 42L
111. val typeT = TypeVariableName("T", Runnable::class, Closeable::class) val typeR = TypeVariableName("R", CharSequence::class) val stringExtToR = LambdaTypeName.get(String::class.asClassName(), returnType = typeR) val tRtoUnit = LambdaTypeName.get(typeT, parameters = typeR.asNullable(), returnType = UNIT) val crazy = FunSpec.builder("crazy") .addModifiers(INLINE) .receiver(stringExtToR) .addTypeVariable(typeT.reified()) .addTypeVariable(typeR) .addParameter("foo", tRtoUnit, NOINLINE) .addStatement("return 42L") .build() inline fun <reified T, R : CharSequence> (String.() -> R).crazy(noinline foo: T.(R?) -> Unit) where T : Runnable, T : Closeable = 42L
112. Kotlin Compatible Code
113. @Nullable public String getSwamp() { return swamp; }
114. @Nullable public String getSwamp() { return swamp; } val swamp: String? = shrek.swamp
115. Bytecode Build tool
116. Bytecode Build tool
117. interface Foo { val bar: String }
118. public abstract interface com/sample/Foo { // access flags 0x401 public abstract getBar()Ljava/lang/String; @Lorg/jetbrains/annotations/NotNull;() // invisible LOCALVARIABLE this Lcom/sample/Foo; L0 L1 0 @Lkotlin/Metadata;(
 mv={1, 1, 7},
 bv={1, 0, 2},
 k=1,
 d1={“…”},
 d2={"Lcom/sample/Foo;", "", "bar", "", “getBar" }
 ) // compiled from: Foo.kt }
119. public abstract interface com/sample/Foo { // access flags 0x401 public abstract getBar()Ljava/lang/String; @Lorg/jetbrains/annotations/NotNull;() // invisible LOCALVARIABLE this Lcom/sample/Foo; L0 L1 0 @Lkotlin/Metadata;(
 mv={1, 1, 7},
 bv={1, 0, 2},
 k=1,
 d1={“…”},
 d2={"Lcom/sample/Foo;", "", "bar", "", “getBar" }
 ) // compiled from: Foo.kt } goo.gl/GcT9gz
120. github.com/Takhion/kotlin-metadata org.jetbrains.kotlin.serialization.ProtoBuf.Class
121. github.com/Takhion/kotlin-metadata org.jetbrains.kotlin.serialization.ProtoBuf.Class
122. github.com/Takhion/kotlin-metadata org.jetbrains.kotlin.serialization.ProtoBuf.Class
123. github.com/Takhion/kotlin-metadata org.jetbrains.kotlin.serialization.ProtoBuf.Class
124. github.com/Takhion/kotlin-metadata org.jetbrains.kotlin.serialization.ProtoBuf.Class
125. github.com/Takhion/kotlin-metadata org.jetbrains.kotlin.serialization.ProtoBuf.Class
126. public abstract interface com/sample/Foo { // access flags 0x401 public abstract getBar()Ljava/lang/String; @Lorg/jetbrains/annotations/NotNull;() // invisible LOCALVARIABLE this Lcom/sample/Foo; L0 L1 0 @Lkotlin/Metadata;(
 mv={1, 1, 7},
 bv={1, 0, 2},
 k=1,
 d1={“…”},
 d2={"Lcom/sample/Foo;", "", "bar", "", “getBar" }
 ) // compiled from: Foo.kt }
127. Bytecode
128. Bytecode
129. public abstract interface com/sample/Foo { // access flags 0x401 public abstract getBar()Ljava/lang/String; @Lorg/jetbrains/annotations/NotNull;() // invisible LOCALVARIABLE this Lcom/sample/Foo; L0 L1 0 @Lkotlin/Metadata;(
 mv={1, 1, 7},
 bv={1, 0, 2},
 k=1,
 d1={“…”},
 d2={"Lcom/sample/Foo;", "", "bar", "", “getBar" }
 )g // compiled from: Foo.kt }A
130. public abstract interface com/sample/Foo { // access flags 0x401 public abstract getBar()Ljava/lang/String; @Lorg/jetbrains/annotations/NotNull;() // invisible LOCALVARIABLE this Lcom/sample/Foo; L0 L1 0 @Lkotlin/Metadata;(
 mv={1, 1, 7},
 bv={1, 0, 2},
 k=1,
 d1={“…”},
 d2={"Lcom/sample/Foo;", "", "bar", "", “getBar" }
 )g // compiled from: Foo.kt }A
131. public abstract interface com/sample/Foo { // access flags 0x401 public abstract getBar()Ljava/lang/String; @Lorg/jetbrains/annotations/NotNull;() // invisible LOCALVARIABLE this Lcom/sample/Foo; L0 L1 0 @Lkotlin/Metadata;(
 mv={1, 1, 7},
 bv={1, 0, 2},
 k=1,
 d1={“…”},
 d2={"Lcom/sample/Foo;", "", "bar", "", “getBar" }
 ) // compiled from: Foo.kt } {A AnnotationVisitor av1 = av0.visitArray("d2"); av1.visit(null, "Lcom/sample/Foo;"); av1.visit(null, ""); av1.visit(null, "bar"); av1.visit(null, ""); av1.visit(null, "getBar"); av1.visit(null, "()I"); av1.visitEnd(); }B {C mv = cw.visitMethod(ACC_PUBLIC + ACC_ABSTRACT, "getBar", "()I", null, null); mv.visitEnd(); }D
132. {A AnnotationVisitor av1 = av0.visitArray("d2"); av1.visit(null, "Lcom/sample/Foo;"); av1.visit(null, ""); av1.visit(null, "bar"); av1.visit(null, ""); av1.visit(null, "getBar"); av1.visit(null, "()I"); av1.visitEnd(); }B {C mv = cw.visitMethod(ACC_PUBLIC + ACC_ABSTRACT, "getBar", "()I", null, null); mv.visitEnd(); }D b b
133. {A AnnotationVisitor av1 = av0.visitArray("d2"); av1.visit(null, "Lcom/sample/Foo;"); av1.visit(null, ""); av1.visit(null, "bar"); av1.visit(null, ""); av1.visit(null, "bar"); av1.visit(null, "()I"); av1.visitEnd(); }B {C mv = cw.visitMethod(ACC_PUBLIC + ACC_ABSTRACT, "bar", "()I", null, null); mv.visitEnd(); }D
134. {A AnnotationVisitor av1 = av0.visitArray("d2"); av1.visit(null, "Lcom/sample/Foo;"); av1.visit(null, ""); av1.visit(null, "bar"); av1.visit(null, ""); av1.visit(null, "bar"); av1.visit(null, "()I"); av1.visitEnd(); }B {C mv = cw.visitMethod(ACC_PUBLIC + ACC_ABSTRACT, "bar", "()I", null, null); mv.visitEnd(); }D
135. { AnnotationVisitor av1 = av0.visitArray("d2"); av1.visit(null, "Lcom/sample/Foo;"); av1.visit(null, ""); av1.visit(null, "bar"); av1.visit(null, ""); av1.visit(null, "bar"); av1.visit(null, "()I"); av1.visitEnd(); } { mv = cw.visitMethod(ACC_PUBLIC + ACC_ABSTRACT, "bar", "()I", null, null); mv.visitEnd(); } public abstract interface com/sample/Foo { // access flags 0x401 public abstract bar()Ljava/lang/String; @Lorg/jetbrains/annotations/NotNull;() // invisible LOCALVARIABLE this Lcom/sample/Foo; L0 L1 0 @Lkotlin/Metadata;(
 mv={1, 1, 7},
 bv={1, 0, 2},
 k=1,
 d1={“…”},
 d2={"Lcom/sample/Foo;", "", "bar", "", “bar” }
 ) // compiled from: Foo.kt }
136. class KotlinFoo(override val bar: Int): Foo
 
 class JavaFoo implements Foo { @Override public int bar() { return 0; } }
137. void setPadding(int l, int t, int r, int b) { // … }
138. void setPadding(int l, int t, int r, int b) { // … }z view.setPadding(10, 0, 0, 10)
139. void setPadding(int l, int t, int r, int b) { // … }z view.setPadding(left = 10, bottom = 10)
140. Bytecode
141. Multiplatform
142. Bytecode
143. Bytecode
144. Bytecode LLVM
145. enum class Direction { NORTH, SOUTH, EAST, WEST } class GamePeice( movement: Set<Direction> = EnumSet.of(Direction.NORTH) )Z
146. enum class Direction { NORTH, SOUTH, EAST, WEST } class GamePeice( movement: Set<Direction> = EnumSet.of(Direction.NORTH) )Z EnumSet.of
147. import java.util.EnumSet enum class Direction { NORTH, SOUTH, EAST, WEST } class GamePeice( movement: Set<Direction> = EnumSet.of(Direction.NORTH) )Z s O EnumSet.of
148. enum class Direction { NORTH, SOUTH, EAST, WEST } class GamePeice( movement: Set<Direction> = setOf(Direction.NORTH) )Z S o
149. import com.google.common.collect @AutoImplement interface Party { val people: ImmutableList<Person> }
150. import com.google.common.collect @AutoImplement interface Party { val people: ImmutableList<Person> } import com.google.common.collect @Generated class AutoParty(override val people: ImmutableList<Person>) : Party
151. CREATE TABLE user( name TEXT NOT NULL, location TEXT AS android.location.Location )
152. CREATE TABLE user( name TEXT NOT NULL, location TEXT AS android.location.Location ) import android.location.Location data class User( val name: String, val location: Location )
153. @file:JvmName("ByteStrings") @JvmName("from") fun ByteArray.asByteString(): ByteString = …
154. @file:JvmName("ByteStrings") @JvmName("from") fun ByteArray.asByteString(): ByteString = … byte[] bytes = … ByteString b = ByteStrings.from(bytes);
155. @file:JvmName("ByteStrings") @JvmName("from") fun ByteArray.asByteString(): ByteString = … byte[] bytes = … ByteString b = ByteStrings.from(bytes); Cannot access 'JvmName': it is internal in 'kotlin.jvm' KT-19507 s
156. @JsName("from") fun ByteArray.asByteString(): ByteString = … @file:JvmName("ByteStrings")
157. @JsName("from") fun ByteArray.asByteString(): ByteString = … @file:JvmName("ByteStrings") KT-19508
158. Verbosity is okay. API is the #1 priority.
159. Verbosity is okay. API is the #1 priority. If you do any kind of Java codegen, keep Kotlin in mind.
160. Verbosity is okay. API is the #1 priority. If you do any kind of Java codegen, keep Kotlin in mind. Don’t depend on platform types unless the user does.
161. KotlinPoet 0.6.0 released!
162. @Strongolopolis & @JakeWharton Kotlin Code Generation