如何从方法Collectors.groupingBy获取有序的Map类型 [英] How to get ordered type of Map from method Collectors.groupingBy

问题描述

我需要按类型将数据列表分为不同的列表，为此，我使用了构造方法

I need to separate list of data into different lists by type, for this purpose I use construction

Map<String,List<Dish>> dishMap = menu.stream()  
         .collect(Collectors.groupingBy(Dish::getType));

但是如何从方法"Collectors.groupingBy"中获取LinkedHashMap而不是HashMap.我在javadoc中发现了一些数据，但无法获得使用该方法必须做的事情:

but How can I get LinkedHashMap instead HashMap from method "Collectors.groupingBy". I found some data in javadoc but I can`t get what I must to do with this method:

Map<String,List<Dish>> dishMap = menu.stream().collect(Collectors.groupingBy(
                Dish::getType,
                LinkedHashMap::new, ????));

我应该在方法"groupingBy"的第三个参数中放置什么以获取所需的信息?

what should I place in the third argument in method "groupingBy" to get what I need?

推荐答案

您应使用 toList Collector :

Map<String,List<Dish>> dishMap = menu.stream().collect(Collectors.groupingBy(
            Dish::getType,
            LinkedHashMap::new, Collectors.toList()));

这篇关于如何从方法Collectors.groupingBy获取有序的Map类型的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！