thenByDescending
inline fun <T> Comparator<T>.thenByDescending(
crossinline selector: (T) -> Comparable<*>?
): Comparator<T>Creates a descending comparator using the primary comparator and the function to transform value to a Comparable instance for comparison.
import kotlin.test.*
fun main(args: Array<String>) {
//sampleStart
val list = listOf("aa", "b", "bb", "a")
val lengthComparator = compareBy<String> { it.length }
println(list.sortedWith(lengthComparator)) // [b, a, aa, bb]
val lengthThenStringDesc = lengthComparator.thenByDescending { it }
println(list.sortedWith(lengthThenStringDesc)) // [b, a, bb, aa]
//sampleEnd
}inline fun <T, K> Comparator<T>.thenByDescending(
comparator: Comparator<in K>,
crossinline selector: (T) -> K
): Comparator<T>Creates a descending 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.
import kotlin.test.*
fun main(args: Array<String>) {
//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
.thenByDescending(String.CASE_INSENSITIVE_ORDER) { it }
println(list.sortedWith(lengthThenCaseInsensitive)) // [b, A, a, bb, aa]
//sampleEnd
}