Kotlin for Android

Basic syntax differences from Java 

Java

Kotlin

Optional

semicolons!

Basic syntax differences from Java 

'fun' keyword

Basic syntax differences from Java 

no more primitive types!

everything is an object

Basic syntax differences from Java 

var & val

keywords

Basic syntax differences from Java 

Java

getters &

setters

as

properties

Basic syntax differences from Java 

String templates

Basic syntax differences from Java 

no 'new' keyword

Basic syntax differences from Java 

Singleton

Basic syntax differences from Java 

JavaBeans...

too much boilerplate code

Basic syntax differences from Java 

so Kotlin comes with...

data classes!

equals() / hashCode(), toString(), copy() 
defined automatically!

Basic syntax differences from Java 

Another key features 

• null safety
• not checked exceptions
• getters & setters
• delegations
• lateinit
• named & optional arguments
• lambdas
• extension functions
• type aliases

Null Safety

nullable references:

safe calls:

Null Safety

too many safe calls?

smart cast (after explicit check) for that:

Null Safety

elvis operator:

!! operator:

safe casts (avoiding ClassCastException):

Getters and Setters

lazy delegation & lateinit

Named & optional arguments

Lambdas

Extension Functions

Type Aliases

Java Interop

Java & Kotlin code in one place:

Java Interop

Calling Java code in Kotlin:

Java Interop

SAM Conversions:

Java Interop

Calling Kotlin code in Java:

Fast configuration

Kotlin Android Extensions

Kotlin Android Extensions

Kotlin Android Extensions

Why Kotlin
for Android?

We have scala, groovy, ceylon...

Kotlin in numbers*...

*from "Using Project Kotlin for Android" by Jake Wharton

More

• Kotlin is developed by JetBrains
• It compiles at least as fast as Java

Any drawbacks?

We are still waiting for Kotlin 1.0

Any drawbacks?

We are still waiting for Kotlin 1.0

"Only very brave souls are using Kotlin for production now" - Andrey Breslav (JetBrains)