Datatype rules for Kotlin.
fun main() {
val myInt = 10
println("default datatype is ${myInt is Int}")
var myLong = 22L
// Every datatype has .toXxxx() functions to convert to another type. In Kotlin, you cannot declare myLong = myInt and expect it to expand the data type.
myLong = myInt.toLong()
val myByte: Byte = 111
var myShort: Short
myShort = myByte.toShort()
var myDouble = 65.984 // Defaults to a Double
println(myDouble is Double) // As proof
val myFloat = 838.9823f // f declares it a Float
println(myFloat is Float) // As proof
// myDouble = myFloat // Will fail - no expansion
myDouble = myFloat.toDouble()
val char = 'b' // Defaults to Char
// char myChar = 65 // In Java would call the char of value 65 = 'A'
val myChar = 65 // In Kotlin, obviously produces a very different result!
// val myChar2: Char = 65 // Fails, does not conform to data type
val myCharInt = 65
println(myCharInt.toChar()) // => A
// When calling Java from Kotlin, how do we provide primitive types since they don't exist in Kotlin?
val vacationTime = false
val onVacation = DummyClass().isVacationTime(vacationTime)
println(onVacation) // Works because the Kotlin datatype classes compile down to primitives. Also works if Java is expecting Boolean due to Java boxing.
// Any, Unit, Nothing classes
// Any is Kotlin root class
val anything: Any
// Unit class is equivalent to void. A Singleton instance of Unit is returned instead of nothing
// Nothing class is subclass of Any class. Could use when e.g. you know something will never return
}