在Kotlin中嵌套的lambda调用

Question

在Kotlin中嵌套lambda调用时,我如何明确地引用child和parent的it元素？例如:

data class Course(var weekday: Int, var time: Int, var duration: Int)
var list1 = mutableListOf<Course>()
var list2 = mutableListOf<Course>()
// populate list1 and list2
// exclude any element from list1 if it has the same time and weekday as any element from list2
list1.filter { list2.none{it.weekday == it.weekday && it.time == it.time} }

Answer 1

it总是引用最里面的lambda参数,要访问外部参数,你必须命名它们.例如:

list1.filter { a -> list2.none { b -> a.weekday == b.weekday && a.time == b.time} }

(你可以把内部的那个留下来it,但是如果你这么说的话,它会更好一点,在我看来.)

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