What's wrong with nested arrays?

Question

Java

Hello everyone
Tell me, what could be wrong with such a design?

ArrayList<ArrayList<Integer>> list = new ArrayList<ArrayList<Integer>>(10);

I read on the forums, they say it's bad ...
Thank you

Answer 1

Where are the arrays?
If you mean ArrayList then it's not an array. If the ones inside the ArrayList is another matter.
In addition to a "tight" binding to a specific implementation of List through ArrayList, I don’t see anything bad.
But in principle, depending on the case, binding to a specific implementation can be beneficial and necessary.
As for me, this option is better.

final List<List<Integer>> list = new ArrayList<>(10);