[CaptainMorgan]

This can probably lead to confusing code down the road, and I would hope someone might have something better but you can try this:

Code:

         ArrayList< ArrayList<String> > my_2dlist = 
                new ArrayList< ArrayList<String> >();
         
         my_2dlist.add( new ArrayList<String>() );
         my_2dlist.get(0).add("Hello, World");
         System.out.println(my_2dlist.get(0).get(0));