what is the best way to create a matrix of array lists (array lists of objects) and how should I initialize it?

Question

I want to create a matrix that contains 5 arrary list. each array list contains different objects but from the same types (they all Actors but every array list contains a different actor...) how should I initialize it? it's basically a game. I want to initialize every actor in the array lists with a position and the general matrix with all the actors/array lists.

Answer 1

create a matrix that contains 5 array lists

ArrayList[] matrix = new ArrayList[5];

each array list contains different objects but from the same types

matrix[0] = new ArrayList<MyCustomClass>();
matrix[0].add(new MyCustomClass(...));
matrix[0].add(new MyCustomClass(...));

how do i get to each actor later

// one way of getting the Actor object if you know 
matrix[0].get(index);the index

If you don't know the index, then you will have to traverse the arraylist and find the Actor you want.