使用lambdaj从嵌套数组中提取对象

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":

我想用lambdaj从嵌套数组中提取一个对象。我的模型是拥有“元素”数组的“产品”列表:

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.

在我的代码中的某个地方,我有一个产品列表,我想在列表中找到一个带有特定代码的元素。

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

根据此讨论:https://groups.google.com/forum/?fromgroups =#!topic / lambdaj / QQGmY3cVHP8,我可以使用:

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...

但不幸的是,这不会编译,因为getElements()是一个数组,而不是一个集合......

So I end up with this java code:

所以我最终得到这个java代码:

 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 ?

有没有办法用lambdaJ迭代嵌套的数组?

1 个解决方案

#1

Ok I found a solution:

好的我找到了解决方案:

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.

这将首先在一个唯一的集合中选择并展平我的所有元素,然后在代码属性上对其进行过滤。

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)

从性能的角度来看,我不确定它是最好的解决方案:看起来好像所有产品和元素在完全扫描完成之前都是扁平化的。 (我对Lambdaj的理解太弱了,不能确定)

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

我认为完整的java实现更有效,因为它在第一个代码匹配时停止。

#1