Extract object from nested array with lambdaj

Question

I want to extract an object from a nested array with lambdaj. My model is a List of "Products" that own an arrays of "Elements":

public class Product {
   Element[] elements;
}
public class Element {
   String code;
}

Somewhere in my code I have a list of Products, and I want to find an Element with a specific code in my list.

According to this discussion: https://groups.google.com/forum/?fromgroups=#!topic/lambdaj/QQGmY3cVHP8, I may use:

select(myproductList,
       having(on(Product.class).getElements()
                .contains(selectUnique(elements, 
                    having(on(Element.class).getCode(), equalTo("codeToFind"))));

But unfortunately, this will not compile because getElements() is an Array and not a Collection...

So I end up with this java code:

 for (Product p : products) {
    for (Element e : p.getElements()) {
       if (e.getCode().equals("codeTofind")) {
           return e;
       }
    }
 }
 return null;

Is there a way to iterate through nested Arrays with lambdaJ ?

Answer 1

Ok I found a solution:

selectFirst(flatten(extract(products, on(Product.class).getElements())),
                          having(on(Element.class).getCode(), equalTo("mycode")));

This will first select and flatten all my elements in a unique collection, then filter it on the code property.

I'm not sure it's the best solution from performance point of view: it looks as if all the products and elements are flattened before a full scan is done. (my understanding of Lambdaj is too weak here to be sure)

I think the full java implementation is more efficient because it stop when the first code is matched.