how to simplify a multi-layer "ArrayList"?

Question

I want to define many variables of type ArrayList<ArrayList<ArrayList<ArrayList<Integer>>>>

But that looks bad.

What I think of now is to create a class like the following

Public class ArrayListMulti{
    ArrayList<ArrayList<ArrayList<ArrayList<Integer>>>> ret;
    public void ArrayListMulti(){
        ret = new ArrayList<>();
    }
    public ArrayList<ArrayList<ArrayList<ArrayList<Integer>>>> getTheArrayList(){
        return ret;
    }
}

But using this method, every time I want to access the ret value, I must call the getTheArrayList method.

Is there an easier way?

Thanks in advance ~

Answer 1

You can extend ArrayList

public class ArrayListMulti extends ArrayList<ArrayList<ArrayList<ArrayList<Integer>>>>{}

Answer 2

Do you really need to have so deep array list? If so, you should thing about providing convenient API of your ArrayListMulti class. For instance, you can add methods like these:

public List<List<List<Integer>>> get(int i) {
    return ret.get(i);
}

public List<List<Integer>> get(int i, int j) {
    return ret.get(i).get(j);
}

...

and so on. (Don't forget to check nested lists for null.)

And one small tip: use a interface, not class when you define a class field (in your case List<List<List<List>>>> ret . It will make your code more robust if you want to change implementation of List interface (eg replace ArrayList to LinkedList ).

Answer 3

use multidimensional array like 3D array or more