Most efficient way of implementing this?

Simple situation really. Just being a bit paranoid I guess.

I have a 2D grid full of objects which I need to represent in source.

The grid contains two objects, object 1 and object 2 which both are children of object 3 which is abstract.
 
Now the thing is I can either:
1. Create an ArrayList<ArrayList> list object. ArrayLists don't care what you store in them so this would work. However it's kind of a hack since I don't really need a re sizable list with all the shit and giggles.

2. Create a packer object. That stores both of objects 1 and object 2 without problems and store then Packer[][] grid = new Packer(); .

So what does /prog/'s wisdom have to say about this? 1, 2 or some new brilliant idea?

Do you not understand the point of inheritance in statically typed languages, or are you just bad at explaining problems?
Alternatively, use a real fucking language.