Introduction of Android and Kotlin to Developers Student clubs leaders from South East Asian countries

1. Hassan Abid
GDE Android - Singapore
@hassanabidpk
Android 101
Kotlin - Future of Android Development

2. ● Mainly work as Android developer
● Google Developers Expert for Android
● Contributed in apps and SDKs: KineMaster, Rakuten LIVE, BeLive, NexPlayer SDK
(Android, iOS, Unity, Tizen)
About me
Lead Software Engineer

3. ● My Android Journey
● Why Kotlin
● Kotlin 101
● Kotlin Vs. Java
● Advance Kotlin
● Learning Resources
Content

4. ● Started learning on my own in 2011 from developers.android.com
● Joined Android Study meetup with Geeks in 2011
● Tried to contribute in a very difficult project in 2011
● Got first internship for developing Tablet UI in 2012 (Life changing move)
● Mentored and taught my friends about Android dev in 2015 (Udacity course)
● Finished Android Nanodegree in dec 2015
● Became Android GDE In 2016
My Android Journey

7. “10 years and now over 2.5 billion active
devices produced by more than 180
hardware manufacturers”
- Android director Stephanie Cuthbertson

8. ● Android Studio 3.5 released
● Kotlin is Google’s preferred language of Android
● Official documentation : https://developer.android.com
● Official Samples : https://developer.android.com/samples
Android
Latest version of Android (10) was released last week

10. Why Kotlin?

11. Kotlin on android since 2017

12. Kotlin popularity
Survey link
In the latest Stack Overflow
developer survey, it ranks
as the fourth-most loved
programming language.

14. Apps built with Kotlin

15. ● Kotlin is a modern statically typed programming language
● It’s pragmatic and concise, and makes coding a satisfying and
efficient experience.
● Kotlin is 100% interoperable with Java
Kotlin 101
Developed by JetBrain

17. Kotlin vs. Java

18. // Kotlin Hello World
fun main(args: Array<String>) {
println("Hello World!")
}
// Java Hello World
class HelloWorld {
public static void main(String[]
args) {
System.out.println("Hello,
World!");
}
}

19. What Kotlin has that
java does not

21. // Nullable types and Non-Null Types
// Case 1
var a: String = "abc"
a = null // compilation error
// Case 2
var b: String? = "abc"
b = null // ok
print(b)

22. // Checking for null in conditions
val b: String? = "Kotlin"
if (b != null && b.length > 0) {
print("String of length ${b.length}")
} else {
print("Empty string")
}

23. // Safe Calls
val a = "Kotlin"
val b: String? = null
println(b?.length)
println(a?.length) // Unnecessary safe call

24. // Safe Calls
val a = "Kotlin"
val b: String? = null
println(b?.length)
println(a?.length) // Unnecessary safe call
// The !! Operator
val l = b!!.length

25. // Extension Functions
fun MutableList<Int>.swap(index1: Int, index2: Int) {
val tmp = this[index1] // 'this' corresponds to the list
this[index1] = this[index2]
this[index2] = tmp
}
// Usage
val list = mutableListOf(1, 2, 3)
list.swap(0, 2) // 'this' inside 'swap()' will hold the value of 'list'

26. // Data Classes
data class User(val name: String = "", val age: Int = 0)
data class Person(val name: String) {
var age: Int = 0
}
val jane = User("Jane", 35)
val (name, age) = jane
println("$name, $age years of age") // prints "Jane, 35 years of age"

27. // Smart Casts
fun demo(x: Any) {
if (x is String) {
print(x.length) // x is automatically cast to String
}
}
// Smart cast for when expression
when (x) {
is Int -> print(x + 1)
is String -> print(x.length + 1)
is IntArray -> print(x.sum())
}

28. ● Read more at https://kotlinlang.org/docs/reference/coroutines-overview.html
● Code Lab : https://codelabs.developers.google.com/codelabs/kotlin-coroutines/#0
Coroutines
Lightweight threads

29. // Async callbacks
networkRequest { result ->
// Successful network request
databaseSave(result) { rows ->
// Result saved
}
}
// The same code with coroutines
val result = networkRequest()
// Successful network request
databaseSave(result)
// Result saved

30. // Android Kotlin Extensions - KTX
// Before KTX
sharedPreferences
.edit() // create an Editor
.putBoolean("key", value)
.apply() // write to disk asynchronously
// After KTX
// Commit a new value asynchronously
sharedPreferences.edit { putBoolean("key", value) }

32. MORE HERE : https://play.kotlinlang.org/hands-on/overview

33. Learning Resources

34. ● Kotlin only docs : https://kotlinlang.org/docs/reference/
● Kotlin for android docs : https://developer.android.com/kotlin
● Android Code Labs for Kotlin : https://codelabs.developers.google.com/?cat=Kotlin
● Android Developers YouTube Channel : https://www.youtube.com/user/androiddevelopers
Official Resources
Kotlin and Android

35. Code Labs

39. Udacity
All courses link
Free courses from Google

40. Udacity
Android Nanodegree link
Basic and Advance Android
Nanodegree

42. Associate Android Developer Certifications
Link :
https://developers.google.com/training/certification/
associate-android-developer/

45. @hassanabidpk
Thank You!