代码示例

filter

val numbers = listOf("one", "two", "three", "four")  
val longerThan3 = numbers.filter { it.length > 3 }
println(longerThan3)

map

val numbers = setOf(1, 2, 3)
println(numbers.map { it * 3 })
println(numbers.mapIndexed { idx, value -> value * idx })

关联

val numbers = listOf("one", "two", "three", "four")
println(numbers.associateWith { it.length })
// 结果如下
// {one=3, two=3, three=5, four=4}