1.
An Introduction
to Kotlin JVM language
Andrius Klimavičius

2.
Intro
• JVM language
• Android and browser support.
• Developed by JetBrains
• Open Source
• First appeared in 2011
• Still in Beta (v1.0.0-beta-3595)

3.
Kotlin
google: kotlin logo

4.
Modern Language for
Industry
• 100% interoperable with Java
• Concise - no boilerplate code
• Safe - convert runtime errors into compile time
• Tools support (command-line, plugins)
• Targets Java 6

5.
Comparison
• Runtime error -> Compile time errors

6.
Kotlin addresses Java
problems
• Null references are controlled by the type system.
• No raw types
• Arrays in Kotlin are invariant
• Kotlin has proper function types, as opposed to Java’s
SAM-conversions
• Kotlin does not have checked exceptions
• Use-site variance without wildcards (<? extends T>)

7.
Kotlin vs Java
• No checked exceptions
• No primitive types that are not classes
• No static members
• No non-private fields
• No wildcard-types

8.
Kotlin vs Java (2)
• Function literals + Inline
functions
• Extension functions
• Null-safety
• Smart casts
• String templates
• Properties
• First-class delegation
• Type inference
• Singletons
• Range expressions
• Operator overloading
• Companion objects

9.
Features
• String templates
• Named arguments & defaults (verbose code)
• Lambda expressions
• Null-Safety (nullable, non-nullable refs)
• Functional programming methods (filter,map,…)
• Extensions (like Objective-C, C#)
• Auto generated POJOs (data class)

10.
Features (2)
• Destructuring Declarations
• Generics (Java)
• Ranges
• Operator Overloading
• Optional semi-colons
• Android support
• ….

11.
Hello World!

12.
Variables

13.
String templates

14.
String templates

15.
Functions

16.
Named params & defaults

17.
Lambda expressions

18.
Null-safety

19.
Basic FP methods like
filtering

20.
Extensions

21.
Data classes

22.
Smart Casts

23.
Call Java from Kotlin
println("Code in Kotlin")

24.
Call Kotlin from Java

25.
Reference
• https://kotlinlang.org
• https://prezi.com/5krzwy15ixea/kotlin-on-
android-mobiconf-2015/