Java Library to query Collections/Objects

Question

I am looking for Java Libraries that will allow me to query collections. I have stumbled across jFilter an JoSql.

However it seems that JoSql has been inactive since 2010 and has had only 2 releases. jFilter seems to be fairly new and hasn't had any new releases since last year.

The small number of search result, when googling either of them, suggests to me that they are not used widely.

Have you got any suggestions regarding these libraries, or know of more active once?

Answer 1

I have used CqEngine successfuly in my company (https://code.google.com/p/cqengine/)

When you instantiate a collection, you can easily define a set of indexes. This is much more powerful than predicates.

Also, when you will perform a search on your collection, CqEngine will not iterate on the whole collection then check if each record matches with the predicate. Instead, it will directly find the matching records in a Map like data structure. Hence you will have excellent performance.

Answer 2

You can look at Commons Collections, and more specifically CollectionUtils.filter(Collection, Filter).

Another option would be Google Guava, which has Iterables.filter(Iterable<T>, Predicate<? super T>).

The choice is yours.

Answer 3

Probably it's too late but it might be helpful for someone else, You could use,

https://code.google.com/p/joquery/

where it supports following syntax,

Collection<Dto> testList = new ArrayList<>();

Filter<Dto> query = CQ.<Dto>filter(testList)
    .where()
    .property("id").eq().value(1);
Collection<Dto> filtered = query.list();

class Dto
{
    private int id;
    private String text;

    public int getId()
    {
        return id;
    }

    public int getText()
    {
        return text;
    }
}