compareBy
Creates a comparator using the sequence of functions to calculate a result of comparison. The functions are called sequentially, receive the given values a
and b
and return Comparable objects. As soon as the Comparable instances returned by a function for a
and b
values do not compare as equal, the result of that comparison is returned from the Comparator.
Since Kotlin
1.0Samples
import kotlin.test.*
fun main() {
//sampleStart
val list = listOf("aa", "b", "bb", "a")
val sorted = list.sortedWith(compareBy(
{ it.length },
{ it }
))
println(sorted) // [a, b, aa, bb]
//sampleEnd
}
Creates a comparator using the function to transform value to a Comparable instance for comparison.
Since Kotlin
1.0Samples
import kotlin.test.*
fun main() {
//sampleStart
val list = listOf("aa", "b", "bb", "a")
val sorted = list.sortedWith(compareBy { it.length })
println(sorted) // [b, a, aa, bb]
//sampleEnd
}
inline fun <T, K> compareBy(comparator: Comparator<in K>, crossinline selector: (T) -> K): Comparator<T>(source)
Creates a comparator using the selector function to transform values being compared and then applying the specified comparator to compare transformed values.
Since Kotlin
1.0Samples
import kotlin.test.*
fun main() {
//sampleStart
val list = listOf('B', 'a', 'A', 'b')
val sorted = list.sortedWith(
compareBy(String.CASE_INSENSITIVE_ORDER) { v -> v.toString() }
)
println(sorted) // [a, A, B, b]
//sampleEnd
}