Arrangements/Combination of a elements in n positions

This method helps in arranging any type of objects in given number of positions. It is brut-force method of getting all type of combinations.

Please leave comments below for more questions and remarks.

public class Solution {
    public static void main(String[] args) {
        List<Integer> a = Arrays.asList(1, 2);
        System.out.println(getArrangements(a, 4));
    }
    public static <T> List<List<T>> getArrangements
               (List<T> numbers, int n) {
        List<List<T>> result = new ArrayList<List<T>>();
        int itr = (int) Math.pow(n, numbers.size());
        for (int i = 0; i < itr; i++) {
            List<T> comb = new ArrayList<T>();
            for (int j = 0; j < n; j++) {
                int pos = (int) Math.pow(numbers.size(),
      (n - j - 1));
                int element = (i / pos) % (numbers.size());
                comb.add(numbers.get(element));
            }
            result.add(comb);
        }
        return result;
    }
}

Results:

Input1:[ 'A','B','C','D'] & 2 positions
output1: [[A, A], [A, B], [A, C], [A, D], [B, A], [B, B], [B, C], [B, D], [C, A], [C, B], [C, C], [C, D], [D, A], [D, B], [D, C], [D, D]]


Input2: [1,2] & 4 positions

[[1, 1, 1, 1], [1, 1, 1, 2], [1, 1, 2, 1], [1, 1, 2, 2], [1, 2, 1, 1], [1, 2, 1, 2], [1, 2, 2, 1], [1, 2, 2, 2], [2, 1, 1, 1], [2, 1, 1, 2], [2, 1, 2, 1], [2, 1, 2, 2], [2, 2, 1, 1], [2, 2, 1, 2], [2, 2, 2, 1], [2, 2, 2, 2]]