Kotlin for Android
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Kotlin is a statically typed programming language for modern multi-platform applications that was created by JetBrains in 2011. It is fully interoperable with Java and offers advantages like concise code, null safety, and tool-friendliness. Google announced support for Kotlin on Android in 2017. The document provides an overview of Kotlin's history and features, examples of using Kotlin on Android, and recommendations for migrating code to Kotlin. It also lists various tutorials, documentation, and sample apps available for learning Kotlin.
Kotlin for Android
- 1. Version 1.0 Kotlin for Android Han Yin @ Jun, 2018 Modern. Expressive. Safe.
- 2. TOC ● Overview, Major advantages, Case study ● Language features by examples ● Migration advices, Tutorials, Documentations & Samples
- 3. Statically typed programming language for modern multi-platform applications. Overview
- 4. Overview: a brief history 2011 JetBrains unveiled Project Kotlin A new language for the JVM, which had been under development for a year. 2012 Open sourced under the Apache 2 license JetBrains hopes that the new language will drive IntelliJ IDEA sales. 2016 Kotlin v1.0 was released on February 15 This is considered to be the first officially stable release and JetBrains has committed to long-term backwards compatibility starting with this version. 2017 Google announced first-class support for Kotlin on Android Android ❤ Kotlin 2018 Kotlin v1.2 was released on November 28 Sharing Code between JVM and Javascript platforms feature was newly added to this release.
- 5. Major advantages @ Language 1 Concise Drastically reduce the amount of boilerplate code. 2 Safe Avoid entire classes of errors such as null pointer exceptions. 3 Inter-operable Leverage existing libraries for the JVM, Android, and the browser. 4 Tool-friendly Choose any Java IDE or build from the command line.
- 6. Major advantages @ Android 1 Compatibility Fully compatible with JDK 6 and Android build system. 2 Performance A Kotlin app runs as fast as an equivalent Java one, due to similar bytecode structure. 3 Footprint Kotlin has a very compact runtime library, which can be further reduced through the use of ProGuard. 4 Compilation Time Incremental builds are usually as fast or faster than with Java, due to efficient incremental compilation.
- 7. Case study 1 Pinterest Successfully introduced Kotlin into their app, used by 150M people every month. 2 Basecamp 100% Kotlin code. Reports a huge difference in developer happiness, great improvements in work quality and speed.
- 8. Language features Range expressions String templates Properties Primary constructors Data classes First-class delegation Companion objects Singletons Null-safety Smart casts Type inference Type projections Declaration-site variance Separate interfaces for read-only and mutable collections Operator overloading Extension functions Inline functions Lambda expressions * Coroutines
- 10. 100% interoperable with Java ● For a Java developer, getting started with Kotlin is very easy. The automated Java to Kotlin converter included in the Kotlin plugin helps with the first steps. ● Kotlin Koans offer a guide through the key features of the language with a series of interactive exercises.
- 11. Null-safety, Mutable & Read-only variable:
- 12. Lateinit
- 13. Elvis operator
- 14. Conditional expressions & When expressions
- 15. Smart casts
- 16. For loops & Range expressions
- 17. Easy bundle: listOf, arrayOf, mapOf, setOf, etc.
- 18. Break, Continue & Return labels
- 19. Named arguments & Default arguments
- 21. Properties & Fields ● To use a property, simply refer to it by name, as if it were a field in Java. ● Fields cannot be declared directly in Kotlin classes. ● However, when a property needs a backing field, Kotlin provides it automatically.
- 22. String templates
- 23. Singleton
- 24. Sealed class
- 27. Extend functionality without inheritance
- 29. Type aliases
- 30. Lazy Evaluation
- 31. Higher-Order Functions & Lambdas
- 33. Filter
- 34. Map
- 35. Reduce
- 36. Performant custom control structures
- 37. Standard functions: run, with, let, also, apply
- 38. Finally, say goodbye to findViewById!
- 39. Android KTX ● Android KTX is a set of Kotlin extensions that is part of the Android Jetpack family. ● It optimizes Jetpack and Android platform APIs for Kotlin use, while doesn’t add any new features to the existing Android APIs. ● The purpose of Android KTX is to make Android development with Kotlin more concise, pleasant, and idiomatic by leveraging Kotlin language features, such as: ○ Extension functions and properties ○ Lambdas ○ Named parameters and parameter default values
- 40. Migration advices and Materials ● Advice from Google ● Advice from Basecamp
- 41. Android Developers: A gradual approach 1. Start by writing tests in Kotlin. Tests are not bundled with your app during packaging, they are a safe place to add Kotlin code. 2. Write new code in Kotlin. Before converting existing Java code, try adding small pieces of new Kotlin code like a small class or top-level helper function. 3. Update existing code to Kotlin. Consider extracting small bits of Java functionality and converting to Kotlin classes and top-level functions. Kotlin fully supported in Android Studio 3.0 and higher
- 42. Basecamp 01 1. Write real production code. It’s something you can see working in your app right away and it’s more fun! That feeling of accomplishment and seeing something work shouldn’t be discounted — it builds your confidence and keeps you motivated. 2. Don’t try to learn the whole language at once Find a few key concepts that click in your brain (not what others tell you are the best parts of the language). Focus just on those concepts and practice using them to their fullest, without feeling overwhelmed.
- 43. Basecamp 02 3. Question all your Java habits Regularly question whether you are doing something the “Kotlin way”. When you see code that feels long or complicated, pause and take another look at it. 4. Use cool downs for Kotlin A great time to work on Kotlin conversions is when you’re cooling down off a big release and watching for stability and customer issues. 5. Learn from the auto converter Auto convert the class, but keep the Java class handy. Put them side by side, and see how the Kotlin compares.
- 44. Tutorials 0 1 How to Kotlin From the Lead Kotlin Language Designer (Google I/O '18) 0 2 Jake Wharton’s talk about Kotlin for Android. From Android KW December 2015 hosted by Matthew P. 0 3 #31DaysOfKotlin From Android Developer Advocates Florina Muntenescu and Sean McQuillan
- 45. Documentations & Samples Kotlin is an open source language with its own documentation and community: 01 | Get Started with Kotlin on Android 02 | Add Kotlin code 03 | Android Kotlin sample apps 04 | Getting started with Android and Kotlin 05 | Kotlin Koans Online 06 | Udacity Kotlin Bootcamp for Programmers
- 46. Thank you!