java 如何使用java-streams将多个列表收集到一个列表中?
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How to collect multiple lists to one list with java-streams?
提问by membersound
How can I collect multiple List
values 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 MyListService
instances 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());