Java 8 Stream filtering value of list in a list

I saw the accepted answer from @kocko which is both a good answer and totally correct. However there is a slightly alternative approach where you simply chain the filters.

final List<MyObject> withBZ = myObjects.stream()
        .filter(myObj -> myObj.getType().equals("B"))
        .filter(myObj -> myObj.getSubTypes().stream().anyMatch("Z"::equals))
        .collect(Collectors.toList());

This is basically doing the same thing but the && operand is removed in favour of another filter. Chaining works really well for the Java 8 Stream API:s and IMO it is easier to read and follow the code.

You can do:

myObjects.stream()
         .filter(t -> t.getType().equals(someotherType) && 
                      t.getSubTypes().stream().anyMatch(<predicate>))
         .collect(Collectors.toList());

This will fetch all the MyObject objects which

• meet a criteria regarding the type member.
• contain objects in the nested List<String> that meet some other criteria, represented with <predicate>