How do I loop thorough a 2D ArrayList in Java and fill it?

Question

I am trying to use 2D arrayLists in Java. I have the definition:

ArrayList> myList = new ArrayList

        

Answer 1

Assuming the matrix is not initialized,

int m = 10, n = 10;
ArrayList> matrix = new ArrayList>();

for (int i = 0; i < m; i++) {
    List row = new ArrayList();
    for (int j = 0; j < n; j++) {
        row.add(j);
    }
    matrix.add(row);
}