How to convert Arraylist<ArrayList<objects>>to ArrayList<objects> [duplicate]

Question

I will elaborate my question further. I have an ArrayList<ArrayList<VehicleLoaded>>, where VehicleLoaded is a class, with several arguments. I want to have all those VehicleLoaded in one ArrayList, is there a way to obtain that?

e.g: I have this:

[
1:[VehicleLoaded100, VehicleLoaded200, VehicleLoaded300,VehicleLoaded400],
2:[VehicleLoaded104,VehicleLoaded205,VehicleLoaded301],
3:[VehicleLoaded650, VehicleLoaded890,VehicleLoaded103]
…
]

and I want to have this:

[VehicleLoaded100, VehicleLoaded200, VehicleLoaded300,VehicleLoaded400,
VehicleLoaded104,VehicleLoaded205,VehicleLoaded301,
VehicleLoaded650, VehicleLoaded890,VehicleLoaded103]

Thank you very much.

Answer 1

You can do it with Streams:

List<VehicleLoaded> list = 
    listOfLists.stream().flatMap(List::stream).collect(Collectors.toList());