从Kotlin的Map获取具有最大值的条目 [英] Get entry with max value from Map in Kotlin

问题描述

我无法理解如何从 Map 界面使用maxBy和maxWith方法.我有以下代码:

I cannot understand how to use maxBy and maxWith methods from Map interface. I have this code:

var myMap: Map<String, Int> = mutableMapOf()
// ...
var best = myMap.maxBy { ??? }

我想获取具有最大值的条目，但我不知道该如何传递给maxBy或maxWith.

I'd like to get the entry with max value but I don't know what to pass to maxBy or maxWith.

推荐答案

MaxBy

MaxBy将值转换为可比较的类型，并按计算出的值进行比较

MaxBy

MaxBy converts the values to a comparable type, and compares by the computed value

MaxWith将各项相互比较，并按比较器的返回值对它们进行排序.

MaxWith compares the items with each other and sorts them by the return value of the comparator.

MaxBy通常更有意义，因为它通常更快(尽管使用YMMV)，而且实现可能更简单，但是如果只能通过比较对项目进行排序，则可能需要使用maxWith.

MaxBy makes more sense usually, because it is usually faster (although YMMV), and because implementations can be simpler, but if the items can only be sorted by comparing then maxWith may be needed.

这将获得最高价值的条目:

This gets the highest value entry:

var maxBy = myMap.maxBy { it.value }

与maxWith相同的代码如下所示:

The same code with maxWith would look like this:

val maxWith = myMap.maxWith(Comparator({a, b -> a.value.compareTo(b.value)}))

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