Through this event, we aimed to educate you on the basics and fundamentals of Kotlin. ->How to get started? ->What are its benefits? This event was EVERYTHING KOTLIN!!

1. Hello To Kotlin
@ArbazPirwani

3. life begins
at the end of your
COMFORT
ZONE-Neale Donald Walsch-

5. Kick Start With Kotlin
Arbaz Pirwani
@arbazpirwani

6. Modern Language

8. 2016 2017 2018 2019 2020
Kotlin Timeline

9. 2016 2017 2018 2019 2020
1.0
Kotlin Timeline

10. 2016 2017 2018 2019 2020
1.0 Google I/O: Kotlin Officially supported language for Android
Kotlin Timeline

11. 2016 2017 2018 2019 2020
1.0
Google I/O: Kotlin Officially supported language for Android
Google I/O: Android goes Kotlin-first
Kotlin Timeline

12. 2016 2017 2018 2019 2020
1.0
Google I/O: Kotlin Officially supported language for Android
Google I/O: Android goes Kotlin-first
Coroutines Preferred
Kotlin Timeline

13. Kotlin Timeline
2016 2017 2018 2019 2020
1.0
Google I/O: Kotlin Officially supported language for Android
Google I/O: Android goes Kotlin-first
You are here
Coroutines Preferred

14. WHY KOTLIN?

15. - Google Preferred Language
- Statistically typed
- Type Inference
- Developed by Jetbrains
- Concise
- 100% interoperable with Java
- Null Safety
- And many more.

16. I don’t like Kotlin

17. I Love Kotlin

18. Java vs Kotlin

19. Java to Kotlin

21. Multiplatform
projects
Server
Kotlin/JVM
Android
Kotlin/JVM
Browser
Kotlin/JS
iOS
Kotlin/Native

23. Question Of The Day
WHY DO KOTLIN AND JAVA PROGRAMMERS WEAR GLASSES?
BECAUSE THEY DON’T SEE SHARP.BECAUSE THEY DON’T SEE SHARP.

24. Tools For Kotlin.

25. https://www.jetbrains.com/idea/download/

26. Why Kotlin?
Expressiveness Safety
Interoperability Structured
concurrency

27. class MainActivity : AppCompatActivity () {
override fun onCreate(savedInstanceState: Bundle?) {
...
fab.setOnClickListener { view ->
Snackbar.make(view,
"Hello ${name.capitalize()}",
Snackbar.LENGTH_LONG).show()
}
fab.backgroundTintList = backgroundTintList
}
}
Why Kotlin?

28. class MainActivity : AppCompatActivity () {
override fun onCreate(savedInstanceState: Bundle?) {
...
fab.setOnClickListener { view ->
Snackbar.make(view,
"Hello ${name.capitalize()}",
Snackbar.LENGTH_LONG).show()
}
fab.backgroundTintList = backgroundTintList
}
}
Nullability in the
type system
Why Kotlin?

29. class MainActivity : AppCompatActivity () {
override fun onCreate(savedInstanceState: Bundle?) {
...
fab.setOnClickListener { view ->
Snackbar.make(view,
"Hello ${name.capitalize()}",
Snackbar.LENGTH_LONG).show()
}
fab.backgroundTintList = backgroundTintList
}
}
Nullability in the
type system
Lambdas
Why Kotlin?

30. class MainActivity : AppCompatActivity () {
override fun onCreate(savedInstanceState: Bundle?) {
...
fab.setOnClickListener { view ->
Snackbar.make(view,
"Hello ${name.capitalize()}",
Snackbar.LENGTH_LONG).show()
}
fab.backgroundTintList = backgroundTintList
}
}
Nullability in the
type system
Lambdas
Extension
functions
Why Kotlin?

31. class MainActivity : AppCompatActivity () {
override fun onCreate(savedInstanceState: Bundle?) {
...
fab.setOnClickListener { view ->
Snackbar.make(view,
"Hello ${name.capitalize()}",
Snackbar.LENGTH_LONG).show()
}
fab.backgroundTintList = backgroundTintList
}
}
Nullability in the
type system
Lambdas
Template
expressions
Extension
functions
Why Kotlin?

32. class MainActivity : AppCompatActivity () {
override fun onCreate(savedInstanceState: Bundle?) {
...
fab.setOnClickListener { view ->
Snackbar.make(view,
"Hello ${name.capitalize()}",
Snackbar.LENGTH_LONG).show()
}
fab.backgroundTintList = backgroundTintList
}
}
Nullability in the
type system
Lambdas
Template
expressions
Extension
functions
Property access
syntax for getters
and setters
Why Kotlin?

33. Kotlin Uptake
60% of Pro Android Developers use Kotlin
70% of Top 1000 Apps contain Kotlin code
Source: Google internal data, May 2020

34. ● Data Classes
● Extension Methods
● Elvis Operator
● Properties
● Default Parameters
● Type Aliases
● Named Parameters
● Spread Operator
● Auto Casts
● Covariance
● Null Safety
● Operator Overloading
● Type Inference
● DSL Support
● Type-Safe Builders
● Coroutines
● String Interpolation
● Ranges
● Map Array Syntax
● Inline Functions
● Sealed Classes
● Delegation
● Destructuring
● KDoc
Coroutine
s

35. Coroutines
● Coroutines are like very light-weight threads
● Asynchronous programming made easy
● No callbacks
● No complex functionality

36. VS

37. Kotlin & Swift
● The syntax of Swift doesn’t just resemble that of Kotlin: in
small chunks of code there can be up to 77% string
similarity.
● At the very least, it should be noted that while Swift
appeared in 2013, Kotlin originated back in 2011. Hence,
even though comparing Kotlin to Swift (in this exact
order) can be convenient due to Swift’s earlier
introduction to a wide audience, any ‘copycat’ attitudes
towards Kotlin aren’t justified.

38. Kotlin & Swift
● Available on both mobile-client and back-end server
● Highly performant and statically-typed
● Kotlin also can be used for web front-end via Kotlin.JS

39. Swift is like Kotlin:
Hello World
Swift
print("Hello, world!")
Kotlin
println("Hello, world!")

40. Swift
var myVariable = 42
myVariable = 50
let myConstant = 42
Kotlin
var myVariable = 42
myVariable = 50
val myConstant = 42
Swift is like Kotlin:
Variables And Constants

41. Swift
let explicitDouble: Double = 42
Kotlin
val explicitDouble: Double = 42.0
Swift is like Kotlin:
Explicit Types

42. Swift
var shoppingList = ["catfish", "water",
"tulips", "blue paint"]
shoppingList[1] = "bottle of water"
Kotlin
val shoppingList = arrayOf("catfish", "water",
"tulips", "blue paint")
shoppingList[1] = "bottle of water"
Swift is like Kotlin:
Arrays

43. Swift
func greet(_ name: String,_ day: String) -> String {
return "Hello (name), today is (day)."
}
greet("Bob", "Tuesday")
Kotlin
fun greet(name: String, day: String): String {
return "Hello $name, today is $day."
}
greet("Bob", "Tuesday")
Swift is like Kotlin:
Functions

44. Swift
class Shape {
var numberOfSides = 0
func simpleDescription() -> String {
return "A shape with (numberOfSides) sides."
}
}
Kotlin
class Shape {
var numberOfSides = 0
fun simpleDescription()
= "A shape with $numberOfSides sides."
}
Swift is like Kotlin:
Classes

45. • Advantages over Java 7 are overwhelming
• Java 8 introduced
• Lambdas
• Null safety (“Optional” class)
• Default methods
• Streams API
• New Date & Time API
Java strikes back with Java 8

46. • Is more elegant, concise and safe
• Has more cool stuff
But even with Java 8 Kotlin still...

48. • Functions - definition in package or in class
• Immutable/mutable variables
• No “new” keyword
• Type inference
• No checked exceptions
• No primitive types
• No static members
Basic syntax and rules
More elegant?

49. • Primary constructors
• No fields, just properties
• Bean style classes easy to declare
• By default, all classes are final
Basic syntax and rules cont’d
More elegant?

50. • Null reference – Billion dollar mistake
• Kotlin is designed in a way that aims to eliminate NPE from our code
Null Safety
More elegant?
Tony Hoare

51. • Declaration-site variance
• out / in generics modifiers
• Supports use-site variance also
• No wildcard syntax, out / in used
Generics
More elegant?

52. MORE COOL STUFF

53. • Default argument values can be defined
• Arguments with default values are optional
• No more need for function overloading (almost)
• Kotlin classes can have only one constructor
• Arguments can be called by name
• When passing arguments by name ordering doesn’t matter
Default arguments and
named arguments

54. • Simpler “is it in range” check
• Can be used for any type that implements Comparable
• “both ends“ included
• “..” operator is translated to “rangeTo” function
• “rangeTo” function is implemented as extension function on
Comparable
• Numerical ranges can be iterated over
• In both directions and in arbitrary steps
Ranges

55. Ranges

56. • Java’s instaceof not very practical
• No !instanceof
• Meet Kotlin’s "is“
• "is" negation "!is“
• Automatic type cast when “is” evaluates true inside if / when
blocks
Pattern matching

57. AND MANY MORE

58. Resources
• https://kotlinlang.org/
• https://play.kotlinlang.org/
• http://nilhcem.com/swift-is-like-kotlin/

59. FreeCodeCamp.org

60. Android Developers

62. Best Kotlin Learning Resources

63. Arbaz Pirwani