Nested lists with streams in Java8

You can do it with flatMap.

I made an example with Company which contains a list of Person :

public static void main(String[] args) {
    List<Company> companies = Arrays.asList(
            new Company(Arrays.asList(new Person("Jon Skeet"), new Person("Linus Torvalds"))),
            new Company(Arrays.asList(new Person("Dennis Ritchie"), new Person("Bjarne Stroustrup"))),
            new Company(Arrays.asList(new Person("James Gosling"), new Person("Patrick Naughton")))
    );

    List<String> persons = companies.stream()
            .flatMap(company -> company.getPersons().stream())
            .map(Person::getName)
            .collect(Collectors.toList());

    System.out.println(persons);
}

Output :

[Jon Skeet, Linus Torvalds, Dennis Ritchie, Bjarne Stroustrup, James Gosling, Patrick Naughton]

You can use two flatMap then a filter then you can pick the first one or if no result return null :

C c1 = listOfAObjects.stream()
        .flatMap(a -> a.getList().stream())
        .flatMap(b -> b.getPr().stream())
        .filter(c -> c.getName().equalsIgnoreCase(name))
        .findFirst()
        .orElse(null);

 listOfObjectsA.stream()
               .flatMap(a -> a.getListOfObjectsB.stream())
               .flatMap(b -> b.getListOfObjectsC().stream())
               .filter(c -> name.equals(c.getName()))
               .findAny()
               .orElse(....)