What you want to get from getRadius()
is every permutation of (x,y)
with x, y ∈ {-2, -1, 1, 2} and |x| ≠ |y|.
int[][] ret = new int[8][2];
int[] set = {-2, -1, 1, 2};
int i = 0;
for(int x : set)
for(int y : set)
if(Math.abs(x) != Math.abs(y)){
ret[i][0] = x;
ret[i][1] = y;
i++;
}