Java 8 Filter list based on condition from the part of the list

sakura :

I have a list of objects N, where N is

N
|--- type (1,2,3)
|--- A (applicable if type 1)
|--- B (applicable if type 2)
|--- C (applicable if type 3)
|--- List<Integer> p 

Now, the result I want is filtered version of List such that:

create a list List<Integer> l

Do this first:

if(type == 1) && (A > some_value):
  Add all elements of p to l
  select this N

Later once L is formed:

if(type != 1)
  if(l contains any element from p):
    select this N

How to achieve this using streams in one step?

I can filter and create a list "l" first and then use that list to filter.

l = stream.filter(a -> a.type == 1 && a.A > some_value).collect(..)

Then, use l to filter further.

But is there a better and precise way?

Andreas :

if(type == 1) && (A > some_value):
  Add all elements of p to l
  select this N

Don't know what "select this N" means here, since you're selecting p values, so I'm ignoring that line.

Set<Integer> set = listOfN.stream()
    .filter(n -> n.type == 1 && n.A > some_value)
    .flatMap(n -> n.p.stream())
    .collect(Collectors.toSet());

For better performance of the next step (contains()), the result was changes from List to Set.

if(type != 1)
  if(l contains any element from p):
    select this N

List<N> result = listOfN.stream()
    .filter(n -> n.type != 1 && n.p.stream().anyMatch(set::contains))
    .collect(Collectors.toList());