Java initialize 2d arraylist

Question

I want to do 2D dynamic ArrayList example:

[1][2][3]
[4][5][6]
[7][8][9]

and i used this code:

 ArrayList

        

Answer 1

If it is not necessary for the inner lists to be specifically ArrayLists, one way of doing such initialization in Java 7 would be as follows:

ArrayList> group = new ArrayList>();
group.add(Arrays.asList(1, 2, 3));
group.add(Arrays.asList(4, 5, 6));
group.add(Arrays.asList(7, 8, 9));
for (List list : group) {
    for (Integer i : list) {
        System.out.print(i+" ");
    }
    System.out.println();
}

Demo on ideone.