Points to ponder from this app about Kotlin:
Koding Efficieny
Cocise Syntax
Avoids boiler plate code (really slick)
Error reduction
Null Safety
Ability to indicate intentions
Excellent compatibility with Java and Android
Singleton pattern for a class is just done using object keyword insted of class (So simple!)
– Automatically instantiated
– All access against same instance
– Member accessed through type name
A class can function as a data model class (like POJO in Java)
– Mark class with data keyword
– Kotlin generates standard methods (equals(), hashCode(), toString())
– Primary constructor must contain only properties
Null safety
Null safe operator
?.
Returns member if not null
like
p?.name
otherwise return null
Elvis operator
?:
returns first operand if not null
otherwise
second operand
explained in Java way:
a != null ? a : b
Example Code:
class Person{
val name: String = "Jim"
var weightLbs: Double = 0.0
var weightKilos: Double
get() = weightLbs / 2.2
set(value){
weightLbs = value * 2.2
}
}
val p = Person()
val name = p.name
p.weightLbs = 220
val kilos = p.weightKilos
p.weightKilos = 50.0
val lbs = p.weightLbs
class Person (val name: String, val weightLbs: Double){
var weightKilos: Double
get() = weightLbs / 2.2
set(value){
weightLbs = value * 2.2
}
fun eatDessert(addedIceCream: Boolean = true){
weightLbs += if (addedIceCream) 4.0 else 2.0
}
fun calcGoalWeightLbs(lbsToLose : Double = 10) : Double {
return weightLbs - lbsToLose
}
}
However, less code in Kotlin could mean less readability and someone coming form Java the syntax seem pretty confusing and obscure!