Why use Purify4J? 
If you want to iterate over a collection is a easiest way to filtering, mapping and ordering. It is a cool way to manipulate collections in Java.
How it works?
It's easy to use. Just add import static com.github.geekonjava.Refination.*; in your class and that's it!
How to use this?
1 - For Filter
First you need a Collection. Here we create a Animal List, and we called it animals.
List<Animal> animals;
Later you goes add a lot of animals in this list.
Now, you want to take all cats, it's easy for Purify4J! In this case, name is a method (animal.name()).
from(animals).where("name", eq("Cat")).all();
Or, would the first animal with 2 year old? Easy too!
from(animals).where("age", eq(2)).first();
2 - For Advance Filter
You can be more specific in your query, adding more specifications, like and and or.
from(animals).where("name", eq("Lion")).and("age", eq(2)).all();
from(animals).where("name", eq("Dog")).or("age", eq(5)).all();
3 - For Matching
There are other matchers to be precise!
eq("Cat")
eqIgnoreCase("Cat")
contains("og")
greaterThan(3)
lessThan(10)
isNull()
Or a special matcher, called not.
not(eq("Bird"))
not(contains("at"))
not(isNull())
4 - For Ordering
Order is a very interesting feature to sort your collection.
from(animals).where("name", eq("Cat")).orderBy("age").all();
from(animals).where("age", eq(5)).orderBy("name", Order.DESC).first();
You can use just order, without filter.
from(animals).orderBy("name");
Hope you like this library and useful for you!