Kotlin != Java

Kotlin is often is treated as a replacement for Java. But in fact, it also supports ctranspilation to JavaScript and compilation to native binaries.

Transcript

1. Kotlin != Java
2. Who am I Oleg Semen • Android dev @ Hustro • Co-Organizer @ KLUG • android ~7y • kotlin ~4y 2
3. Sliced but whole 2 A pre-story of a little adventure in multiplatform world 3
4. 4 feet, 8.5 inches 143.51 centimetres
13. Sliced but whole 2 A pre-story of a little adventure in multiplatform world 13
14. 2 Sliced buttholes A little adventure in space on the chariot 14
18. Why Kotlin is better • null safe • 100% interoperability and backward compatibility • the best tooling support • pragmatic
19. What exactly is better ? • null safety • data classes • extension functions • delegates • dsl • functional paradigm • sealed classes • inline classes • reified generic types (fixes type erasure) • named method arguments • default method values • more
20. dsl.kt data class Person (var name: String? = null, var age: Int = 0) fun person(block: Person.() -> Unit): Person = Person().apply(block)
21. dsl.kt data class Person (var name: String? = null, var age: Int = 0) fun person(block: Person.() -> Unit): Person = Person().apply(block)
22. dsl.kt data class Person (var name: String? = null, var age: Int = 0) fun person(block: Person.() -> Unit): Person = Person().apply(block)
23. dsl.kt data class Person (var name: String? = null, var age: Int = 0) fun person(block: Person.() -> Unit): Person = Person().apply(block)
24. dsl.kt data class Person (var name: String? = null, var age: Int = 0) fun person(block: Person.() -> Unit): Person = Person().apply(block)
25. dsl.kt data class Person (var name: String? = null, var age: Int = 0) fun person(block: Person.() -> Unit): Person = Person().apply(block)
26. dsl.kt data class Person (var name: String? = null, var age: Int = 0) fun person(block: Person.() -> Unit): Person = Person().apply(block)
27. dsl.kt data class Person (var name: String? = null, var age: Int = 0) fun person(block: Person.() -> Unit): Person = Person().apply(block)
28. dsl.kt data class Person (var name: String? = null, var age: Int = 0) fun person(block: Person.() -> Unit): Person = Person().apply(block) fun main() { val p = person( { name = "Name" age = 10 }) }
29. dsl.kt data class Person (var name: String? = null, var age: Int = 0) fun person(block: Person.() -> Unit): Person = Person().apply(block) fun main() { val p = person() { name = "Name" age = 10 } }
30. dsl.kt data class Person (var name: String? = null, var age: Int = 0) fun person(block: Person.() -> Unit): Person = Person().apply(block) fun main() { val p = person { name = "Name" age = 10 } }
31. decompiled dsl.kt public final class DslKt { @NotNull public static final Person person(@NotNull Function1 block) { Intrinsics.checkParameterIsNotNull(block, "block"); Person var1 = new Person((String)null, 0, 3, (DefaultConstructorMarker)null); boolean var2 = false; boolean var3 = false; block.invoke(var1); return var1; } }
32. decompiled dsl.kt public final class DslKt { @NotNull public static final Person person(@NotNull Function1 block) { Intrinsics.checkParameterIsNotNull(block, "block"); Person var1 = new Person((String)null, 0, 3, (DefaultConstructorMarker)null); boolean var2 = false; boolean var3 = false; block.invoke(var1); return var1; } } WTF
33. decompiled Main.java class Main { public static void main(String[] args) { Person p = DslKt.person(person -> { person.setName("Name"); person.setAge(10); return null; }); } }
34. https://www.youtube.com/watch? v=COK73uaNgCo
35. vs
36. vs
37. vs
41. https://habr.com/ru/company/redmadrobot/blog/351516/
42. var ktNotJs = function (_, Kotlin) { //……. function person(block) { var $receiver = new Person(); block($receiver); return $receiver; } //…. _.Person = Person; _.person_nrnvvi$ = person; _.main = main; main(); Kotlin.defineModule('ktNotJs', _); return _; }
43. index.js console.log( ktNotJs.person_nrnvvi$(function (a) { a.name = "Name"; a.age = 10; }) );
44. fun main() { console.log( person { name = "Name" age = 10 } ) }
46. main.c/main.cpp
48. class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) sample_text.text = stringFromJNI() } external fun stringFromJNI(): String companion object { init { System.loadLibrary("native-lib") } } }
49. Summary class Kotlin extends Java
50. Summary class Kotlin extends Java class Kotlin: Java by ByteCode(), JavaScript by Transpilation(), Native by Compilation()
54. Let’s be friends • twitter.com/OlegSemen1 • fb.com/oleh.semen • semenoh@gmail.com • twitter.com/klug64299104 • fb.com/kotlinLviv • lviv.kotlinUserGroup@gmail.com Follow KLUG 54