Foreach loop through Java Hashmap in Lua

Question

So I'm new to Lua and I've got LuaJava running with my Java code, but I'm stuck trying to figure out how to run a foreach loop on a hashmap in Lua.

In my java code I have this:

Java

public class EntityManager {

    public static EntityManager EntityManager = new EntityManager();

    private Map<Integer, Entity> entities = new HashMap<Integer, Entity>();

    public Map<Integer, Entity> entities() {
        return entities;
    }
        ....
}

public class Entity {
    private int id;
    ....
    public int getId() {
        return id;
    }

    public EntityManager getManager() {
        return EntityManager.EntityManager;
    }
}

Then I've got my lua script and I'm trying to figure out how to iterate through all entities in the hashmap in EntityManager:

Lua

owner = {} -- I set this to an Java object that is a child of the Entity class
function doSomeStuff()
    for i, e in pairs(owner:getManager():entities()) do
        if (e:getId() ~= owner:getId()) then
            -- Do some stuff here
        end
    end
end

I've pretty much got everything I need set up for my functions, etc. to work but I don't know how to go about creating a Lua equivalent of a Java foreach loop, to iterate through my Java hashmap in my Lua script.

Also I'd like to know how I can check the type of an object in Lua to see if it's an instanceof one of my Java classes. For example, in Java if I wanted to see if an object is of an object type I would do the following:

Entity e;
....
if (e instanceof EntityTypeA) {
    // e is of Entity type A
} else if (e instanceof EntityTypeB)
    // e is of Entity type B
}

Oh, and I'm not entirely sure if the Java object I'm passing into the Lua script is retaining it's Java class type, nor do I know how to go about doing such a thing.

By the way, I'm using LuaJava from Kepler Project.

Thanks.