Transformation from Java-Kotlin to Kotlin Style Programming

This is a talk in Kotlin Everywhere in Boston conducted on the 8th and 9th of November 2019
In this talk I walk thru the basics of the baggage that a developer with experience in Kotlin carries and how it can be reduced when writing the code in Kotlin.

Link to the talk
https://www.youtube.com/watch?v=SMa8EaYlGrU&list=PLHNdTenpo3pieslLcqGfqBV4a6pXFOZCC&index=23&t=0s

Transcript

1. Transformation from Java-Kotlin to Kotlin styled programming Nithin Kumar Putchakayala @nithinpvnk
2. transformation from Java-Kotlin to Kotlin styled programming Nithin Kumar Putchakayala @nithinpvnk My ^
3. Kotlin • Unveiled by Jetbrains in 2011, 1.0 was released in 2016 • Given first class support in 2017 by Google • Android made Kotlin-first in 2019 by Google 3 @nithinpvnk
4. 4 @nithinpvnk
5. 5 @nithinpvnk
6. 6 @nithinpvnk
7. “ This code block looks like a case of writing Java code in Kotlin.” 7 @nithinpvnk
8. Java-Kotlin Kotlin 8 What is Java-Kotlin? Kotlin @nithinpvnk
9. Java Kotlin 9 • Synthetic attributes • Safe call • Built-in extensions • Lambdas @nithinpvnk
10. But how to? • Data classes • Sealed classes • Null Safety • Built-in extensions 10 @nithinpvnk
11. 4th most loved feature of Kotlin Highly used feature Data Classes @nithinpvnk 11
12. Java Java - Kotlin Kotlin 12 @nithinpvnk
13. Java-Kotlin Kotlin 13 @nithinpvnk • All the parameters need to be either val or var • Cannot be abstract, open inner or sealed • Can implement interfaces or sealed classes
14. • Classes used for restricted hierarchies • Feature which is kind of a hack in Java Sealed Classes @nithinpvnk 14
15. Java Java - Kotlin 15 @nithinpvnk
16. Java-Kotlin Kotlin 16 @nithinpvnk
17. Null Safety 17 @nithinpvnk
18. 18 “The Billion dollar mistake” - C. A. R. Hoare @nithinpvnk
19. Java Java - Kotlin 19 @nithinpvnk
20. Java-Kotlin Kotlin 20 The above code could cause a NPE and crash the app @nithinpvnk
21. Extension Function 21 @nithinpvnk
22. Built-in Extension Functions let with run also emptylist apply take Unless takeIf decapitalize replaceAfter endsWith format zipWithNext singleOrNull capitalize replace retainAll maxBy remove associateBy times minBy elementAtOrNull minus filterNot takeLast fold plus windowed reduce shuffle zip filterNotNull contains firstOrNull filterTo swap asReversed map mutableListOf mapIndexedNotNull flatten flatMap groupBy slice take dropWhile chunked sortedDescending reversed union binarySearch drop takeWhile fill takeWhileLast 22 @nithinpvnk
23. Java Kotlin 23 Let @nithinpvnk
24. 24 Let @nithinpvnk • Has context object available as an argument called by default as “it” • Used to introduce local variables with a limited scope for readability • Invoke nested calls to functions
25. Java Kotlin 25 Apply @nithinpvnk
26. 26 @nithinpvnk • Run(Object reference “this”) is similar to Let(Object reference “it”) • Also(Object reference “it”) is similar to Apply(Object reference “this”)
27. 27 @nithinpvnk • Let (Object reference “it”) : Executing lambda on non-null objects Introducing variable in local scope • Run (Object reference “this”) : Object configuration with computation of result • Apply(Object reference “this”) : Object Configuration • Also(Object reference “it”) : Additional effects
28. Java Kotlin 28 Map and Filter @nithinpvnk
29. 29 @nithinpvnk
30. • Make use of Data and Sealed classes • Understand and respect nullability • Utilize built-in extension functions • Learn and update on the feature set available 30 @nithinpvnk
31. 31 @nithinpvnk
32. Thank you 32 @nithinpvnk Twitter and IG - @nithinpvnk Linkedin - https://www.linkedin.com/in/venkatankp