Writing Java-friendly Kotlin code. Sergey Ryabov

Transcription

1 Writing Java-friendly Kotlin code Sergey Ryabov

2 compile 'rxbinding:x.y.x' compile 'rxbinding-appcompat-v7:x.y.x' compile 'rxbinding-design:x.y.x' compile 'autodispose:x.y.z' compile 'autodispose-android:x.y.z' compile 'autodispose-android-archcomponents:x.y.z'

3 compile 'rxbinding:x.y.x' compile 'rxbinding-kotlin:x.y.x' compile 'rxbinding-appcompat-v7:x.y.x' compile 'rxbinding-appcompat-v7-kotlin:x.y.x' compile 'rxbinding-design:x.y.x' compile 'rxbinding-design-kotlin:x.y.x' compile 'autodispose:x.y.z' compile 'autodispose-kotlin:x.y.z' compile 'autodispose-android:x.y.z' compile 'autodispose-android-kotlin:x.y.z' compile 'autodispose-android-archcomponents:x.y.z' compile 'autodispose-android-archcomponents-kotlin:x.y.z'

4 JAVA

5 JAVA volatile synchronized strictfp transient

6 @Transient

7 @Transient package kotlin.jvm

8 ANALYTICS ABSTRACTION LIBRARY

9 ANALYTICS ABSTRACTION LIBRARY object Analytics { fun send(event: Event) {} fun addplugins(plugs: List<Plugin>) {} fun getplugins(): List<Plugin> {} }

10 ANALYTICS ABSTRACTION LIBRARY object Analytics { fun send(event: Event) {} fun addplugins(plugs: List<Plugin>) {} fun getplugins(): List<Plugin> {} } interface Plugin { fun init() fun send(event: Event) fun close() }

11 ANALYTICS ABSTRACTION LIBRARY object Analytics { fun send(event: Event) {} fun addplugins(plugs: List<Plugin>) {} fun getplugins(): List<Plugin> {} } interface Plugin { fun init() fun send(event: Event) fun close() } data class Event( val name: String, val context: Map<String, Any> = emptymap() )

12 TIME FOR SOME CODE!

13 Generics 8

14 VARIANCE

15 VARIANCE Animal Dog

16 VARIANCE Animal Dog

17 VARIANCE ArrayList<Animal> ArrayList<Dog>

18 VARIANCE INVARIANT ArrayList<Animal> ArrayList<Dog>

19 VARIANCE INVARIANT ArrayList<Animal> ArrayList<Dog> Iterator<Animal> Iterator<Dog>

20 VARIANCE INVARIANT ArrayList<Animal> ArrayList<Dog> Iterator<Animal> Iterator<Dog>

21 VARIANCE INVARIANT ArrayList<Animal> ArrayList<Dog> COVARIANT Iterator<Animal> Iterator<Dog>

22 VARIANCE INVARIANT ArrayList<Animal> ArrayList<Dog> COVARIANT Iterator<Animal> Iterator<Dog> Action<Animal> Action<Dog>

23 VARIANCE INVARIANT ArrayList<Animal> ArrayList<Dog> COVARIANT Iterator<Animal> Iterator<Dog> Action<Animal> Action<Dog>

24 VARIANCE INVARIANT ArrayList<Animal> ArrayList<Dog> COVARIANT Iterator<Animal> Iterator<Dog> CONTRAVARIANT Action<Animal> Action<Dog>

25 VARIANCE // Java List<Dog> dogs = new ArrayList<>(); List<Animal>kanimals = dogs;

26 VARIANCE // Java List<Dog> dogs = new ArrayList<>(); List<Animal>kanimals = dogs;

27 USE-SITE VS DECLARATION-SITE VARIANCE // Java List<Dog> dogs = new ArrayList<>(); List<? extends Animal> animals = dogs;

28 USE-SITE VS DECLARATION-SITE VARIANCE // Java List<Dog> dogs = new ArrayList<>(); List<? extends Animal> animals = dogs; // Kotlin val dogs: List<Dog> = ArrayList() val animals: List<Animal> = dogs

29 USE-SITE VS DECLARATION-SITE VARIANCE // Java List<Dog> dogs = new ArrayList<>(); List<? extends Animal> animals = dogs; // Kotlin val dogs: List<Dog> = ArrayList() val animals: List<Animal> = dogs interface List<out E> : Collection<E>

30 USE-SITE VS DECLARATION-SITE VARIANCE // Java List<Dog> dogs = new ArrayList<>(); List<? extends Animal> animals = dogs; // Kotlin val dogs: List<Dog> = ArrayList() val animals: List<Animal> = dogs interface List<out E> : Collection<E>

31 14 NOW BACK TO THE CODE

32 MAY THE ANNOTATIONS BE

33 WORTH NOTING

34 WORTH NOTING Inline functions

35 WORTH NOTING Inline functions Reified type params

36 WORTH NOTING Inline functions Reified type params java.lang.class

37 WORTH NOTING Inline functions Reified type params java.lang.class Unit

38 WORTH NOTING Inline functions Reified type params java.lang.class Unit Typealiases

39 WORTH NOTING Inline functions Reified type params java.lang.class Unit Typealiases Visibility

40 WORTH NOTING Inline functions Reified type params java.lang.class Unit Typealiases internal visibility (!)

41 Writing Java-friendly Kotlin