Kotlin迭代器要列出? [英] Kotlin iterator to list?

问题描述

我有一个来自 fieldNames :

I have an iterator of strings from fieldNames of JsonNode:

val mm = ... //JsonNode
val xs = mm.fieldNames()

我想在保持计数的同时遍历字段，例如:

I want to loop over the fields while keeping count, something like:

when mm.size() {
  1 -> myFunction1(xs[0])
  2 -> myFunction2(xs[0], xs[1])
  3 -> myFunction3(xs[0], xs[1], xs[2])
  else -> print("invalid")
}

显然，上面的代码不起作用，因为xs不能像这样对Iterator建立索引.我试图查看是否可以通过mm.toList()将迭代器转换为列表，但是不存在.

Obviously the above code does not work as xs the Iterator cannot be indexed like so. I tried to see if I can convert the iterator to list by mm.toList() but that does not exist.

我该如何实现?

推荐答案

可能最简单的方法是先将迭代器转换为Sequence，然后再转换为List:

Probably the easiest way is to convert iterator to Sequence first and then to List:

listOf(1,2,3).iterator().asSequence().toList()

结果:

[1, 2, 3]

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