Why I Left Java for Kotlin

https://www.meetup.com/RVA-Software-Development-User-Group/events/270789325/

Transcript

1. Why I Left Java
   For Kotlin
   Sam Edwards - @HandstandSam
   

   View Slide

2. Sam Edwards
   

   View Slide

3. Outline
   ●The Current State of Java & Kotlin
   
   ●Live Coding - Kotlin Language Features
   
   ●What Else is Possible with Kotlin
   
   ●Conclusion
   

   View Slide

4. I Love Java
   ❤
   

   View Slide

5. My First…
   • Job out of college was writing Java
   • Google App Engine Backend
   • Android app was written in Java
   

   View Slide

6. Java 6?
   Who is Using "
   

   View Slide

7. Java 7?
   Who is Using
   #
   $
   

   View Slide

8. Java 8?
   Who is Using
   &$
   '()
   #'
   

   View Slide

9. Java 9,10,11,12,13,14?
   Who is Using
   *
   

   View Slide

10. Java Releases
    https://en.wikipedia.org/wiki/Java_version_history
    10
    

    View Slide

11. Java Releases
    11
    J2SE 1.4 February 2002
    J2SE 5.0 September 2004
    Java SE 6 December 2006
    Java SE 7 July 2011
    Java SE 8 (LTS) March 2014
    Java SE 9 September 2017
    Java SE 10 March 2018
    Java SE 11 (LTS) September 2018
    Java SE 12 March 2019
    Java SE 13 September 2019
    https://en.wikipedia.org/wiki/Java_version_history
    

    View Slide

12. Kotlin
    

    View Slide

13. Kotlin
    13
    

    View Slide

14. Android Community Driven Adoption
    

    View Slide

15. Officially Supported Language (2017)
    

    View Slide

16. Preferred Language for Android (2019)
    

    View Slide

17. View Slide

18. View Slide

19. View Slide

20. Kotlin Releases
    • Started - 2010
    
    • 1.0 - 2016
    
    • 1.1 - 2017
    
    • 1.2 - 2017
    
    • 1.3 - 2018
    
    • 1.4 - Almost… 2020…
    

    View Slide

21. Fast Evolution of Kotlin
    ●Decoupled From Java Virtual Machine (JVM)
    
    ●Compiler Plugin + Standard Libraries -> Java Bytecode
    

    View Slide

22. View Slide

23. View Slide

24. It’s The Little Things
    

    View Slide

25. View Slide

26. Why I Left Java for Kotlin - Live Coding
    https://github.com/handstandsam/why-i-left-java-for-kotlin
    

    View Slide

27. My Favorite Features
    ●Java Interop
    
    ●Extension Functions
    
    ●Ability to Convert Java -> Kotlin
    
    ●Null Safety
    
    ●Data Classes
    
    ●Immutability (val)
    
    ●Named Parameters
    
    ●No “new” or “;”
    
    ●Higher Order Functions & Lambdas
    
    ●Sealed Classes
    
    ●Coroutines - Reactive Programming
    

    View Slide

28. Coroutines
    

    View Slide

29. Kotlin Coroutines
    Explained in one slide
    • A function with a suspend keyword signifies it must run in a Coroutine

    

    suspend fun doNetworkRequest() : Result {

    // Network Request Occurs

    }
    
    • suspend functions must be executed within a CoroutineContext and Once
    inside a coroutine, code executes sequentially

    

    CoroutineContext(Dispatchers.Default).launch{

    val result = doNetworkRequest()

    processResult(result)

    }
    

    View Slide

30. “Essentially, coroutines are light-weight
    threads. They are launched in a context
    of some CoroutineScope.”
    

    View Slide

31. “Essentially, coroutines are light-weight
    threads. They are launched in a context
    of some CoroutineScope.”
    

    View Slide

32. (Developer) Happiness
    

    View Slide

33. Developer Happiness is REAL
    

    View Slide

34. Developer Happiness
    ●Less Boilerplate
    
    ●Concise & Readable Code
    
    ●Handle Nullable Values Proactively
    
    ●Don’t have to throw away Java code
    
    ●Enables Functional Programming
    
    ●Enables Reactive Programming
    

    View Slide

35. Kotlin Adoption
    

    View Slide

36. GitHub Repositories Created in 2020
    ● Java: 1,034,837

    https://github.com/search?q=created%3A%3E2019-01-01+language%3AJava&type=Repositories&ref=advsearch&l=Java&l=
    
    
    ● Kotlin: 100,798 

    https://github.com/search?q=created%3A%3E2020-01-01+language%3Akotlin&type=Repositories
    

    View Slide

37. What Else is Possible with Kotlin?
    

    View Slide

38. Kotlin Multiplatform
    ●Android + iOS Code Sharing
    
    ●JavaScript
    
    ●Mac, Linux, Window
    

    View Slide

39. Multiplatform Libraries
    https://github.com/AAkira/Kotlin-Multiplatform-Libraries
    

    View Slide

40. Kotlin Native
    

    View Slide

41. Not All Roses
    
    

    View Slide

42. Not All Roses
    ●Non-Ideal Interop For Some Java Frameworks and
    Libraries
    
    ●Pick the right tool for the job
    
    ●Not everyone knows Kotlin yet
    
    ●Your team may not want to do Kotlin because it’s too
    “risky”
    

    View Slide

43. I Love Kotlin
    ❤
    

    View Slide

44. Dear Java,
    
    You taught me about NullPointerExceptions, verbose
    code and mutable data. I will always love you, but
    I’ve met a language named Kotlin, and I’m moving on.
    
    Love,
    
    -Sam
    
    

    View Slide

45. Why I Left Java
    
    For Kotlin
    Sam Edwards - @HandstandSam
    Thank You!
    

    View Slide

46. View Slide

47. Kotlin to Java Bytecode
    

    View Slide

48. Kotlin Compilation to Java Bytecode
    Code.kt Code.class
    Kotlin Compiler
    

    View Slide

49. Java Decompiler (Using Fernflower)
    Code.class Java Decompiler Code.java
    

    View Slide

50. Magic
    Code.kt Code.class
    Kotlin Compiler Java Decompiler Code.java
    

    View Slide

51. Code.kt Code.class
    Kotlin
    Compiler
    Java
    Decompiler
    Code.java
    

    View Slide