markdown Java - 将2层/级别集合映射到集合

Posted 2021-05-06

Mapping a 2 layers collection level `Set<Set<T>>` to a 1 level collection `Set<T>`

``` java
Set<T> entity = list.stream()
\!h  .flatMap(ent -> ent.getItens().stream())
  .collect(Collectors.toSet());
```

Take into consideration that:
- `ent.getItens()` returns a `Set<T>`