> For the complete documentation index, see [llms.txt](https://jihoony.gitbook.io/developers-notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jihoony.gitbook.io/developers-notes/developer/readme/etcs/list-of-lists-into-a-list-stream.md).

# List of Lists into a List (Stream)

## Required

> Stream Support Since Java 1.8

## Use FlatMap

Use `FlatMap` to flatten the internal lists into a single Stream, and the collect the result into a list:

```java
List<List<Object>> list = .....
List<Object> flat = list.stream()
                .flatMap(List::stream)
                .collect(Collectors.toList());
```

{% embed url="<https://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html#flatMap-java.util.function.Function->" %}