Question

I know that for arrays you can add an element in a two dimensional array this way:

 array[0][1] = 17; //just an example

How can I do the same thing with ArrayList?

Answer 1

myList.get(0).set(1, 17);

maybe?

This assumes a nested ArrayList, i.e.

ArrayList<ArrayList<Integer>> myList;

And to pick on your choice of words: This assigns a value to a specific place in the inner list, it doesn’t add one. But so does your code example, as arrays are of a fixed size, so you have to create them in the right size and then assign values to the individual element slots.

If you actually want to add an element, then of course it’s .add(17), but that’s not what your code did, so I went with the code above.