java 如何使用java-streams将多个列表收集到一个列表中?

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时间:2020-11-03 02:40:50  来源:igfitidea点击:

How to collect multiple lists to one list with java-streams?

javajava-stream

提问by membersound

How can I collect multiple Listvalues into one list, using java-streams?

如何使用 将多个List值收集到一个列表中java-streams

List<MyListService> services;

services.stream().XXX.collect(Collectors.toList());


interface MyListService {
   List<MyObject> getObjects();
}

As I have full control over the interface: or should I change the method to return an Arrayinstead of a List?

因为我可以完全控制界面:还是应该更改方法以返回数组而不是列表?

回答by Eran

You can collect the Lists contained in the MyListServiceinstances with flatMap:

您可以使用以下命令收集MyListService实例中包含的列表flatMap

List<MyObject> list = services.stream()
                              .flatMap(s -> s.getObjects().stream())
                              .collect(Collectors.toList());