Kotlin

Transcript

2. Guess What…? It’s QUESTION TIME!
3. • Statically typed programming language • A variety of tools around it • It’s a stable, very capable platform • The JVM with JIT is fast enough for just about anything • Being a garbage collected language means there is a whole class of problems I can ignore Things that make me like Java and JVM
4. Things that make me dislike Java • It’s very verbose and repetitive • Boilerplate • Everything is a nail (class) • A Nullability problem • Checked exceptions
5. Defensive programming
6. Defensive programming
7. Defensive programming
8. Defensive programming
9. Boilerplate
11. Lombok projectlombok.org
13. What is Kotlin? • Statically typed programming language developed by JetBrains (IntelliJ) • Open sourced in 2011, Kotlin 1.0 released on Feb 15th of 2016 • 100% interoperable with Java • On Google I/O 2017 became first class citizen language on Android
14. Why Kotlin? • Costs nothing to adopt • Concise language • No runtime overhead • Solves the Nullability problem • Great Interoperability • Familiar syntax • Lots of modern features
15. Lots of modern features • Null safety • No checked exceptions • Extension functions • High-order functions • Function types & lambdas • Default & named arguments • Properties • Type inference • Operator overloading • Smart casts • Data classes • Immutable collections • Enhanced switch-case • String interpolation • Ranges • Inline functions • Infix notations • Tail recursion • Coroutines (async/await) from 1.3 • Great Standard Library
16. Lots of modern features • Null safety • No checked exceptions • Extension functions • High-order functions • Function types & lambdas • Default & named arguments • Properties • Type inference • Operator overloading • Smart casts • Data classes • Immutable collections • Enhanced switch-case • String interpolation • Ranges • Inline functions • Infix notations • Tail recursion • Coroutines (async/await) from 1.3 • Great Standard Library • 100% Java interoperable • Similar syntax • Great community • Compiles to Java 6 bytecode • Great tooling • Rapid development
17. What Java has that Kotlin doesn’t • Checked exceptions • Primitive types that are not classes • Static members • Non-private fields • Wildcard-types • Ternary-operator a ? b : c
18. Favourite features pusher.com/state-of-kotlin
19. Familiar syntax
20. Null safety
21. String interpolation Java Kotlin
22. Smart cast Java Kotlin
23. Intuitive equals Kotlin Java
24. Default arguments Java Kotlin
25. Named arguments Java Kotlin
26. When expression
27. When expression
28. The Data class
29. The Data class
30. Operator overloading
31. Destructuring declaration
32. Destructuring declaration
33. Delegation in Kotlin
34. Type aliases
35. Type aliases
36. Inline classes* * since 1.3
37. Inline classes* * since 1.3
38. Extension functions Java Kotlin
39. Kotlin and stdlib
40. Kotlin and FP
41. Kotlin and FP arrow-kt.io
42. Kotlin and FP
43. Migrating Java to Kotlin pusher.com/state-of-kotlin
44. Kotlin and Testing
45. Kotlin and Testing spekframework.org
46. Kotlin and Testing github.com/kotlintest/kotlintest
47. Kotlin and Testing
48. Kotlin and Testing github.com/nhaarman/mockito-kotlin
49. Kotlin and Testing
50. Kotlin and Testing Method beforeClass() should be static
51. Kotlin and Testing
52. Kotlin and Testing org.junit.internal.runners.rules.ValidationError: The @Rule 'timeout' must be public
53. Kotlin and Testing youtrack.jetbrains.com/issue/KT-3441
54. Kotlin and Spring Kotlin: 
 By default, all classes and methods are final Spring: • @Configuration doesn’t work • Proxy can’t be created Kotlin: • Write open everywhere • Take a look at the plugins: all-open or kotlin-spring
55. Kotlin and Spring
56. Kotlin and Spring
57. Kotlin and Spring
58. Kotlin and Spring
59. Kotlin and Spring github.com/spring-projects/spring-boot/issues/11343 * Don’t forget to add spring-koltin which contains jackson-module-kotlin
60. Kotlin and Spring youtrack.jetbrains.com/issue/KT-11475
61. • Nullability support in Spring: jira.spring.io/browse/SPR-15540 (closed) • @NonNullApi, @NonNullFields, etc. (JSR-305) • Reactor, Spring-Data-Mongo, Spring-Data-Cassandra with null-safety support Kotlin, Spring and null
62. Spring Kotlin DSL spring.io/blog/2017/08/01/spring-framework-5-kotlin-apis-the-functional-way
63. Kotlin DSL github.com/fkorotkov/k8s-kotlin-dsl
64. Kotlin Gradle DSL github.com/Barlog-M/gradle-kotlin-dsl-example
65. Kotlin and static analysis github.com/arturbosch/detekt
66. Kotlin and static analysis github.com/arturbosch/sonar-kotlin
67. Formatting in Kotlin
68. Formatting in Kotlin
69. Formatting in Kotlin github.com/shyiko/ktlint
70. Current state of Kotlin
71. Kotlin JS Scenarios for compiling Kotlin to JS: • Creating Kotlin code that targets client-side JS: • Interacting with DOM elements • Interacting with graphics such as WebGL • Creating Kotlin code that targets server-side JS: • Working with server-side technology (Node.js) kotlinlang.org/docs/reference/js-overview.html
72. Kotlin JS github.com/Barlog-M/kotlin-js-webpack-example
73. Kotlin Native Target platforms: • Windows (x86_64 only at the moment) • Linux (x86_64, arm32, MIPS, MIPS little endian) • MacOS (x86_64) • iOS (arm32 and arm64) • Android (arm32 and arm64) • WebAssambly (wasm32 only) github.com/JetBrains/kotlin-native/tree/master/samples
74. Questions over time sotagtrends.com/?tags=[kotlin,scala,groovy,go,rust]&relative=true
75. Most popular technologies (22) insights.stackoverflow.com/survey/2018/#technology-programming-scripting-and-markup-languages
76. Most Loved and Wanted insights.stackoverflow.com/survey/2018/#most-loved-dreaded-and-wanted
77. The “source” of developers pusher.com/state-of-kotlin
78. What Kotlin is used for https://www.jetbrains.com/research/devecosystem-2018/kotlin/
79. How long have you been using Kotlin? www.jetbrains.com/research/devecosystem-2018/kotlin
80. Ratio of Kotlin in your main codebase pusher.com/state-of-kotlin
81. How to start? • Kotlin homepage and documentation: kotlinlang.org • Slack: kotlinlang.slack.com • Kotlin links: kotlin.link • KEEP: https://github.com/Kotlin/KEEP • Kotlin weekly: www.kotlinweekly.net
82. viartemev Go try Kotlin!