How To Kotlin

Points to cover

• Java interoperability
• Type inference
• Smart cast
• Method references
• inline if-else and try-catch
• Expression body methods
• Default closed classes
• Null safety
• default parameters and named parameters
• infix methods
• Extension functions
• String templates
• Compile time constants using const
• lateinit and delegated properties
• Operator overloading
• Arrays
• Collections
• Object expressions and declarations (Singleton, anonymous objects etc.)
• Range expressions
• Data classes
• Higher-Order Functions and Lambdas

lateinit and delegated properties

Property delegates don’t have to implement any interface, but they have to provide a getValue() function (and setValue()

val lazyGuy: LazyGuy by lazy { LazyGuy("is always late") }

• TODO

Helpful functions right out of the box.

fun toBeImplemented() {
    TODO("Your reason")
}

Written as expression body

fun toBeImplemented() = TODO("Your reason")

• Named and default arguments

• Classes are final by default

class Pet(val name: String)

class Dog(name: String):Pet(name) // WON'T WORK: Pet is default final

We need to specify the open keyword

open class Pet(val name: String)

• inlined if-else

fun testThis(str: String) = if(str.lenght > 2) "Test1" else "Test2"

• inline try-catch