如何使用Java 8按某些特定键的值对地图列表进行排序? [英] How can I sort a list of maps by value of some specific key using Java 8?

问题描述

如何使用Java 8对Map<String, String>的List进行排序?该映射包含一个名为last_name的键，并且与之关联的值可能是null.我不确定该怎么做，因为以下情况会导致编译器错误:

How can I sort a List of Map<String, String> using Java 8? The map contains a key called last_name, and the value associated with it may be null. I'm not sure how to do it because the following results in a compiler error:

List<Map<String, String>> peopleList = ...

peopleList.sort(Comparator.comparing(Map::get, Comparator.nullsLast(Comparator.naturalOrder())));

使用匿名类是唯一的方法吗?

Is using an anonymous class the only way to do it?

请注意，我不尝试对列表中的每个地图进行排序.我想根据每个地图中的键对列表本身进行排序.

Note that I am not trying to sort each map in the list. I want to sort the list itself based on a key in each map.

推荐答案

看起来您可以像这样重写代码

It looks like you can rewrite your code like

peopleList.sort(Comparator.comparing(
                    m -> m.get("yourKey"), 
                    Comparator.nullsLast(Comparator.naturalOrder()))
               )

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