thenBy
inline fun <T> Comparator<T>.thenBy(crossinline selector: (T) -> Comparable<*>?): Comparator<T>(source)
Creates a comparator comparing values after the primary comparator defined them equal. It uses 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 lengthComparator = compareBy<String> { it.length }
println(list.sortedWith(lengthComparator)) // [b, a, aa, bb]
val lengthThenString = lengthComparator.thenBy { it }
println(list.sortedWith(lengthThenString)) // [a, b, aa, bb]
//sampleEnd
}inline fun <T, K> Comparator<T>.thenBy(comparator: Comparator<in K>, crossinline selector: (T) -> K): Comparator<T>(source)
Creates a comparator comparing values after the primary comparator defined them equal. It uses the selector function to transform values and then compares them with the given comparator.
Since Kotlin
1.0Samples
import kotlin.test.*
fun main() {
//sampleStart
val list = listOf("A", "aa", "b", "bb", "a")
val lengthComparator = compareBy<String> { it.length }
println(list.sortedWith(lengthComparator)) // [A, b, a, aa, bb]
val lengthThenCaseInsensitive = lengthComparator
.thenBy(String.CASE_INSENSITIVE_ORDER) { it }
println(list.sortedWith(lengthThenCaseInsensitive)) // [A, a, b, aa, bb]
//sampleEnd
}