Two level filtering of list in Java 8

Question

I have a list aList of objects of class A. This aList is member of each element b of another list bList. Each element b is of class B. Structure of class B is as follows:

class B {
    String status;
    String name;
}

Structure of class A is as follows:

class A {
    List<B> bList;
    String status;
}

Now I would like to filter aList as follows:

Final list aListResult should contain object a only if a.status = "Active" as well as each "Active" a of aList should contain bList of only "Active" b objects i.e. if b will be in associated bList if and only if b.status == Active.

How would I achieve that in Java 8, I cannot figure out.

Answer 1

I'm assuming you want the output List to contain only active A instances for which all the associated B instances are active:

List<A> aList = ...;
List<A> aListResult = 
    aList.stream()
        .filter(a -> a.getStatus().equals("Active"))
        .filter(a -> a.bList.stream().allMatch(b -> b.getStatus().equals("Active")))
        .collect(Collectors.toList());