Kotlin:  An interoperability story

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Kotlin:  An interoperability story Yan Zhulanow, JetBrains Nov 2018

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Good Java interoperability  from the very beginning

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Good Java interoperability  from the very beginning Because we needed it  for our projects

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Compiles to JVM bytecode equals? Good Java interoperability

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Compiles to JVM bytecode equals? Good Java interoperability NO.

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String? Nullable types

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val name: String = null

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val name: String = null Null can not be a value of a non-null type String

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val name: String? = null name.length

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val name: String? = null name.length Only safe (?.) or non-null asserted (!!.) calls are allowed

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System.getProperty("my.property") String String? What about Java?

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System.getProperty("my.property") String? What about Java?

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class DetailsActivity : FragmentActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setOrientation( getResources()!! .getConfiguration()!! .getOrientation()!!) getSupportFragmentManager()!! .beginTransaction()!! .add(android.R.id.content, DetailsFragment())!! .commit() } }

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String! Platform types

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Interoperable with Java

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Interoperable with Java Ecosystem

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Interoperable with Java Ecosystem Build tools Post-processors Analyzers Frameworks IDE

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class Worker { @field:Inject var log: Logger? = null fun process(task: Task) { log?.debug("$task started") task.run() log?.debug("$task ended") } }

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class Worker { @field:Inject var log: Logger? = null fun process(task: Task) { log?.debug("$task started") task.run() log?.debug("$task ended") } }

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class Worker { @field:Inject lateinit var log: Logger fun process(task: Task) { log.debug("$task started") task.run() log.debug("$task ended") } }

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@field:Inject Annotations with use-site targets

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allopen noarg sam-with-receiver Compiler plugins

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Inspections Java AST

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UAST  (universal AST) Java AST Kotlin AST Inspections

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Interoperable with Java

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Interoperable with Java Android

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Tiny runtime around 1 MB

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Dalvik/ART support

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Tooling support Build tools, Lint, Android Extensions

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Annotation processor support Dagger, ButterKnife, the rest 9000 of them

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Kotlin 1.3  Multi-platform projects!

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Java Android Interoperable with

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Java Android JavaScript Interoperable with

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Java Android JavaScript C Interoperable with

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Java Android JavaScript C  Objective-C Interoperable with

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Java Android JavaScript C  Objective-C Swift Interoperable with

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Java Android JavaScript C  Objective-C Swift ??? Interoperable with

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Java Android JavaScript C  Objective-C Swift ??? Interoperable with ecosystem

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We ❤ Kotlin. And we want to use it everywhere. because

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We ❤ Kotlin. And we want to use it everywhere. because Back-end Front-end Android iOS Embedded Games Scripting ICPC Desktop Science