Nested lists with streams in Java8

Question

I have a list of objects A. Each object A in this list contains list of object B and the object B contains list of Object C. The object C contains an attribute name that i w

Answer 1

I had same task but i had one nested class. And I had to filter the objects with filter in the nested collection. As a result, I had to get items that have matches in the collection.

for example:

public class RootElement {
    private String name;
    private List nestedElements;

    //getters / setters and constructors
}

init collection with elements:

List elements = Arrays.asList(
                new RootElement("first", Arrays.asList("one", "two", "three")),
                new RootElement("second", Arrays.asList("four", "one", "two")));

filter example:

String filterParam = "four";
        List filtered = elements.stream()
                .flatMap(root -> root.getNestedElements()
                        .stream()
                        .filter(nested -> nested.equalsIgnoreCase(filterParam))
                        .map(filteredElement -> new RootElement(root.getName(), root.getNestedElement())))
                .collect(Collectors.toList());

Hope it will help someone.