val pair: Pair<String, Int> = "myKey" to 2
What is a Pair Type?
A utility class when you want to return 2 values that are not related to one another.
Some examples
val (a, b) = Pair(1, "x")
println(a) // 1
println(b) // x
Alterantively, you could use:
val p = Pair("x", "y")
println(p) // (x, y)
You can refer to it as first and second
val p = Pair("x", "y")
println(p.first) // x
println(p.second) // y
This is great for returning multiple values from a function.
The to keyword
The shorter version of doing this, is to use a map value with the to keyword:
val p = "x" to "y"
println(p.first) // x
println(p.second) // y
Or:
val p = Pair("x" to "y")
println(p.first) // x
println(p.second) // y
Using Pairs in function return Types
fun main() {
val p = getMyPairs()
println(p) // (x, y)
}
fun getMyPairs() : Pair<String, String> {
return Pair("x", "y")
}
And splitting into values:
fun main() {
val (first, second) = getMyPairs()
println(first) // x
println(second) // y
}
fun getMyPairs() : Pair<String, String> {
return Pair("x", "y")
}
Simplifying getMyPairs
fun getMyPairs() : Pair<String, String> {
return"x" to "y"
}
Comparing to a mapOf
fun main() {
val myMap = mapOf("x" to "y", "z" to "o")
println(myMap) // {x=y, z=o}
}
