Modern Android Development with Kotlin

This presentation talks about Kotlin: the new language for building native Android Applications

Transcript

1. Modern Android Development with Kotlin GDG DevFest Ikorodu 2018
2. Hi, I’m Adora Full Stack Web Developer Google Associate Android Developer Writer, adorahack.com Twitter: @theadoranwodo, @adorahack GitHub: @adoranwodo 2
3. 3 From Java to Kotlin
4. ▣ Runs on the JVM ▣ Statically typed language ▣ Gets rid of Java NullPointerException ▣ Interoperable ▣ Safer code ▣ Gets rid of boilerplate code ▣ Modern programming language ▣ Easier way to develop Android apps 4 Why Kotlin?
5. Enterprise Application Server 5 JavaScript Android Development Web
6. JAVA public class Person{ private String firstname, lastname; public Person(String fname, String lname){ this.firstname = fname; this.lastname = lname; } public String getFirstname(){ return firstname; } public String getLastname(){ return lastname; } Public void setFirstname(string firstname){ this.firstname = firstname; } Public void setLastname(string firstname){ this.lastname = lastname; } } KOTLIN data class Person(var firstname: String, var lastname: String) 6 Code less. Do more.
8. Syntax Let’s write some code 1. Basic Types 2. Switch 2.0 - When 3. Data Class 4. Sealed Class 5. Lambda Expressions 8
9. 9 Basic Types var a: Int = 100 var b: Float = 100.00f var c: Char = ‘a’ var isDeveloper: Boolean = true var name: String = “Adora” val numbers: IntArray = intArrayOf(1,2,3,4,5,6,7,8,9,0) val numbers: MutableList<Int> = mutableListOf(1, 2, 3) val readOnlyNumbers: List<Int> = numbers
10. Simple form when (x) { 1 -> print("x == 1") 2 -> print("x == 2") else -> { print("x is neither 1 nor 2") } } 10 Switch 2.0 - When Multiple cases when (x) { 0, 1 -> print("x == 0 or x == 1") else -> print("otherwise") } Range when (x) { in 1..10 -> print("x is in the range") in validNumbers -> print("x is valid") !in 10..20 -> print("x is outside the range") else -> print("none of the above") }
11. 11 Data Class data class Person(var firstname: String, var lastname: String) val person = Person(“Nenne”, “Nwodo”) //no new keyword print(person.firstname) // prints Nenne print(person.lastname) // prints Nwodo
12. 12 Sealed Class Sealed classes are used when a value can have only one of the types from a limited set (restricted hierarchies). Sealed classes cannot have public constructors sealed class Animal{} class Monkey: Animal() class Dog: Animal() Fun animalType (a: Animal) = when(a){ Is Monkey -> print(“Monkey”) Is Dog -> print(“Dog”) }
13. 13 Lambda Expressions Higher order functions take functions as a parameter and returns a function. Lambda reduces boilerplate code Fun sampleFunction(x: String, doStuff: (String)->String){ //higher order function doStuff(x) } //lambda expression val doStuff: (String) -> String = { s -> “Hello $s” } sampleFunction(“Adora”, doStuff)
14. Tools Want to make things easier than they already are? 1. Anko 2. Kotlin Android Extensions 3. RxKotlin 4. Spek 5. Kotson 14
15. Anko Super hero Kotlin Library for Android Anko consists of a lot of extension functions to make Android development easier 15
17. Kotlin Android Extensions Goodbye, findViewById Say hello to Synthetic binding 17
18. RxKotlin Kotlin extensions for RXJava RxKotlin is a lightweight library that adds convenient extension functions to RxJava. 18
20. Spek Write Tests Rewrite of Spek with Kotlin Multi Platform framework in mind. Reworked in Specification & Gherkin. 20
22. Kotson Gson for Kotlin Parse and write JSON with Google’s Gson using a conciser and easier syntax 22
24. ArtXLagos App for the ArtXLagos fair built in Kotlin 24
25. 25 Play Sample app built in Kotlin
26. 26 Med manager Android App to track medication intake and compliance.
27. Who uses Kotlin? 27
28. How do I get started? ▣ Udacity ▣ Udemy ▣ Lynda ▣ https://kotlinlang.org/ ▣ https://developer.android.com/kotlin/ ▣ https://github.com/JetBrains/kotlin 28
29. build for fun 29
30. build for yourself 30
31. build for the future 31
32. build in android 32
33. Thanks! 33 Website - www.adoranwodo.com Blog - www.adorahack.com GitHub - @adoranwodo Twitter - @theadoranwodo, @adorahack